Testing system

Abstract

This invention provides a test system for testing devices having multiple electrical contacts. [Solution] The test system comprises a device table operable to hold at least one device under test; a probe including at least one probe end for contacting the electrical contacts of the device under test; a moving mechanism operable to move one or both of the device table and the probe to bring at least one probe end into contact with at least one electrical contact of the device under test; and a profile determination system configured to determine the profile of the electrical contacts of the device under test.

Description

Technical Field

[0001] The present invention relates to a test system. In particular, the present invention relates to a test system for testing the integrity of electronic devices.

Background Art

[0002] The electronic device to be tested may include, for example, a semiconductor device (e.g., an integrated circuit). After manufacturing the electronic device, it is desirable to test the device. For example, the integrity of one or more circuits within the electronic device can be tested.

[0003] A method of testing an electronic device may include, for example, the steps of inputting an electronic signal (e.g., a pulse signal) into the device and measuring any reflection of the signal from the device. If the device includes an open circuit or a short circuit within its circuit, the signal input into the device will be at least partially reflected. If there are no defects in the device, the input signal will be hardly or not at all reflected from the device. Therefore, the measured value of the reflected signal from the device under test (DUT) can be used to test the integrity of the device and detect any defects within the device.

[0004] A test system suitable for testing a DUT has been previously proposed, for example, in US20140021963, which is hereby incorporated by reference in its entirety.

[0005] The object of the present invention is to provide an improved test system that removes or alleviates one or more problems of the prior art, whether or not specified herein.

Summary of the Invention

[0006] According to a first aspect of the present invention, a test system is provided for testing a device having a plurality of electrical contacts, the test system comprising: a device table operable to hold at least one device under test; a probe including at least one probe end for contacting the electrical contacts of the device under test; a moving mechanism operable to move one or both of the device table and the probe to bring at least one probe end into contact with at least one electrical contact of the device under test; and a profile determination system configured to determine the profile of the electrical contacts of the device under test.

[0007] A profile determination system may be configured to determine the three-dimensional profile of the electrical contacts of the device under test. The determined profile may include multiple locations where the surfaces of the electrical contacts are positioned. For example, the determined profile may include the determined height of the electrical contacts at different locations on the device under test. A profile determination system may be configured to determine the profile of the device under test, including the region of the device under test positioned between the electrical contacts. The profile may include, for example, the height of the device under test at different locations on the device under test.

[0008] The location, size, and / or shape of the electrical contacts of a device under test may differ between devices and may not be known before testing the device. The profile of the electrical contacts of the device under test, determined by a profile determination system, can be used to determine the position where the probe should be moved (relative to the device table) for the probe end to contact the electrical contacts of the device under test. A moving mechanism can move one or both of the device table and the probe to the determined position, allowing the probe end to contact the electrical contacts. This may enable an automated process to be performed in which the probe can be connected to the electrical contacts in order to test the device through the electrical contacts.

[0009] Automated processes can significantly reduce the time required to test a device (compared to manually moving a probe to make contact with electrical contacts). In some embodiments, the moving mechanism can move one or both of the device table and the probe to make contact with multiple different electrical contacts at different times. This can allow the device to be tested through multiple different electrical contacts. In such embodiments, the time required to test the device through multiple different electrical contacts is significantly reduced by an automated system for making contact with the electrical contacts at the end of the probe.

[0010] The moving mechanism may be operable to translate one or both of the device table and / or probe, and / or to rotate one or both of the device table and / or probe. In general, the moving mechanism may be operable to change the position and / or orientation of the device table and / or probe, or to perform any movement of the device table and / or probe.

[0011] The probe may have at least two probe ends, and the moving mechanism may be operable to bring at least two probe ends into contact with at least two electrical contacts of the device under test. At least two probe ends may be in contact with at least two electrical contacts simultaneously.

[0012] The device under test may include a grounding plate. The grounding plate may be a separate element from the rest of the device and may be placed on the device for the purpose of testing the device. A grounding plate located on the device is considered to form part of the device under test. Furthermore, the grounding plate is considered to be an example of an electrical contact on the device under test that the probe end can contact. In this specification, any reference to contacting an electrical contact on the device under test includes contacting a grounding plate located on the device.

[0013] The profile determination system may include a radiation source configured to irradiate at least a portion of the device under test with radiation, a radiation sensor configured to detect radiation scattered from the electrical contacts of the device under test, and a controller configured to determine the profile of the electrical contacts of the device under test from the detected scattered radiation.

[0014] Radiation scattered from different parts of the device under test may appear at different locations within the field of view of the radiation sensor. The controller can determine the location on the device under test from which the scattered radiation is being scattered, based on the locations within the field of view where the scattered radiation appears. This may allow for the determination of the location and / or shape of the scattering surface of the device under test.

[0015] The radiation sensor may be positioned such that different parts of the device under test, extending by different amounts away from the device table, appear at different positions within the radiation sensor's field of view.

[0016] This ensures that radiation scattered from different distances from the device table appears at different locations within the field of view of the radiation sensor. Therefore, the location within the field of view where the scattered radiation appears allows for the determination of the distance from the device table from which the radiation is scattered. This allows for the determination of the heights of different points on the device under test, and thus a profile of the device under test can be derived.

[0017] The radiation sensor may be oriented at an oblique angle to the direction of propagation of the radiation emitted from the radiation source.

[0018] The radiation source may be configured to irradiate a strip of the device under test with a radiation strip.

[0019] The radiation sensor may be configured to detect radiation scattered from electrical contacts located within the radiation strip, and the controller may be configured to determine the height of a point on the device under test located within the irradiated strip.

[0020] The moving mechanism may be capable of moving either or both the device table and the radiation source to scan a radiation strip on the device under test, and the controller is configured to determine the profile of the electrical contacts of the device under test by combining the heights of determined points on the device under test at different locations on the radiation strip.

[0021] The device table may include multiple reference structures extending outside or into the device table, and the profile determination system is configured to determine the position of the profile of the electrical contacts of the device under test relative to the positions of the reference structures.

[0022] The reference structure provides a known reference point from which the position of the electrical contacts of the device under test can be determined by comparison. Recognizing the position of the electrical contacts relative to the reference structure allows for the determination of the position to which the probe should be moved to make contact with the electrical contacts.

[0023] The reference structures may extend from the device table, and at least two of the reference structures may extend outside the device table by different distances.

[0024] The moving mechanism may be operable to move one or both of the device table and / or the probe so that at least one of the probe ends comes into contact with one of the reference structures.

[0025] The test system may further include a calibration system configured to enable the determination of the position of at least one probe end relative to a reference structure.

[0026] Determining the position of the probe tip relative to the reference structure enables the probe tip to be brought into exact contact with the reference structure. This provides a reference point for the known configuration of the movement mechanism that results in a known position of the probe relative to the device table. This may enable other configurations of the movement mechanism that result in other positions of the probe relative to the device table to be determined. By recognizing the position of the electrical contact relative to the device table, the probe can be accurately moved to contact the desired electrical contact.

[0027] The calibration system may be the same as the profile determination system. For example, the position of at least one probe tip relative to the reference structure can be determined using the same procedure as for determining the profile of the electrical contact. Instead, different procedures may be used. For example, the calibration system may include a camera or microscope that can be used to directly observe the position of the probe tip relative to the reference structure.

[0028] The movement mechanism can be adjusted manually while observing the position of the probe tip relative to the reference structure (e.g., through a camera or microscope) until the probe tip is brought into contact with the reference structure.

[0029] In some embodiments, the calibration system may include means for detecting contact between the probe tip and the reference structure. For example, the calibration system may include an electrical continuity tester that detects electrical continuity between the probe tip and the reference structure. The calibration system may also include one or more pressure sensors on the probe and / or the reference structure configured to detect contact between the probe tip and the reference structure.

[0030] The profile determination system can be further configured to determine the position of the probe tip relative to the electrical contacts of the device under test.

[0031] This may allow the probe's position relative to the device under test and / or device table to be determined. This allows the calibration of the probe's position relative to the device table to be updated during the test procedure for testing the device under test.

[0032] The profile determination system can determine, for example, the position of the probe end relative to the electrical contacts of the device under test when the probe end is close to the electrical contacts.

[0033] The test system further comprises a controller configured to determine, from the determined profile of the electrical contacts of the device under test, the configuration of a moving mechanism that brings at least one probe end into contact with at least one electrical contact of the device under test.

[0034] A second aspect of the present invention provides a test system for testing a device having a plurality of electrical contacts, the test system comprising: a device table operable to hold at least one device under test; a probe including at least one probe end for contacting an electrical contact of the device under test; and a moving mechanism operable to move one or both of the device table and the probe to bring at least one probe end into contact with at least one electrical contact of the device under test, wherein the device table includes a plurality of reference structures extending out of or into the device table.

[0035] A reference structure provides a reference point at a known position on the device table. Calibration can be performed to determine the position of the electrical contacts and probe end of the device under test relative to the reference structure. Determining the positions of the electrical contacts and probe end relative to the reference structure makes it possible to determine the position of the probe end relative to the electrical contacts. This allows a moving mechanism to move either or both the device table and the probe, bringing the probe end into precise contact with the electrical contacts, thereby enabling the probe to test the device under test through the electrical contacts.

[0036] The device table may comprise at least three reference structures. In some embodiments, the device table may comprise three or more reference structures, for example, eight reference structures.

[0037] The probe may have at least two probe ends, and the moving mechanism may be operable to bring at least two probe ends into contact with at least two electrical contacts on the device under test. At least two probe ends may be in contact with at least two electrical contacts simultaneously.

[0038] The device under test may include a grounding plate. The grounding plate may be a separate element from the rest of the device and may be placed on the device for the purpose of testing the device. A grounding plate located on the device is considered to form part of the device under test. Furthermore, the grounding plate is considered to be an example of an electrical contact on the device under test that the probe end can contact. In this specification, any reference to contacting an electrical contact on the device under test includes contacting a grounding plate located on the device.

[0039] At least two of the reference structures extend either outside or inside the device table by different distances.

[0040] At least two reference structures extending outside or inside the device table by different distances advantageously improve the accuracy with which the positions of features (e.g., electrical contacts and one or more probe ends) can be determined relative to the reference structures. In some embodiments, all reference structures may extend outside or inside the device table by approximately the same distance. However, in such embodiments, accurately making contact between electrical contacts located at different heights may depend on the accuracy and linearity of the profile determination system. By placing the reference structures at different heights (i.e., extending outside or inside the device table by different distances), references at different heights can be obtained. This may allow any nonlinearity or scaling errors in the profile determination system to be compensated for, and the accuracy with which electrical contacts located at different heights are made can be improved.

[0041] The distance a reference structure extends outside or inside the device table may be called the height of the reference structure. The area of ​​the device table configured to support at least one device under test may be located substantially within the support surface. The distance a reference structure extends outside or inside the device table may be the distance perpendicular to the support surface. In some embodiments, the reference structure may extend from the support surface, and the distance a reference structure extends outside or inside the device table may be the distance a reference structure extends from the support surface. In other embodiments, the reference structure may extend from a surface other than the support surface. For example, the reference structure may be positioned at different perpendicular levels with respect to the support surface. The reference structure may extend from a surface substantially parallel to the support surface. The distance a reference structure extends outside or inside the device table may be the distance a reference structure extends from a surface substantially parallel to the support surface.

[0042] The moving mechanism may be operable to move one or both of the device table and / or the probe so that at least one of the probe ends comes into contact with one of the reference structures.

[0043] The moving mechanism can be manually operated to bring the probe end into contact with a reference structure. For example, the probe end and the reference structure can be viewed through a camera or microscope, and the moving mechanism can be manually operated while viewing the probe end and the reference structure through the camera or microscope. The moving mechanism can be guided to bring the probe end into contact with the reference structure.

[0044] The test system may further include a calibration system configured to enable the determination of the position of at least one probe end relative to a reference structure.

[0045] As described above, referring to the first aspect, determining the position of the probe end relative to the reference structure allows the probe end to make precise contact with the reference structure. This provides a reference point for a known configuration of the moving mechanism that results in a known position of the probe relative to the device table. This may allow other configurations of the moving mechanism that result in other positions of the probe relative to the device table to be determined. By recognizing the position of the electrical contacts relative to the device table, the probe can be precisely moved to make contact with the desired electrical contacts.

[0046] For example, the calibration system may include a camera or microscope that can be used to directly observe the position of the probe end relative to a reference structure. Alternatively, the calibration system may include a profile determination system as described in relation to the first embodiment.

[0047] In some embodiments, the calibration system may include means for detecting contact between the probe end and the reference structure. For example, the calibration system may include an electrical continuity tester for detecting electrical continuity between the probe end and the reference structure. The calibration system may also include one or more pressure sensors on the probe and / or the reference structure, configured to detect contact between the probe end and the reference structure.

[0048] At least one of the reference structures may include a reference feature section indicating a reference point on the reference structure, and the moving mechanism is operable to move one or both of the device table and the probe so that at least one of the probe ends contacts the reference point.

[0049] The reference feature section provides a more accurate positional reference point, allowing the probe end to be precisely moved. This improves the accuracy of measuring the probe's position relative to the device table. The reference feature section provides a point on a reference structure that can be resolved by inspection (direct visual inspection or inspection using an inspection device (e.g., camera or microscope)). This allows the probe end to be guided to contact the reference point.

[0050] The reference feature may be provided on a convex or protruding surface of the reference structure. This can reduce the possibility of the probe end unintentionally coming into contact with other areas of the reference structure.

[0051] The reference feature may, for example, include a circular groove within the reference structure, and the probe end may be in contact with a reference point located within the area enclosed by the circular groove. The reference feature may, for example, surround the vertex of the reference structure. For example, in an embodiment in which the reference structure includes a circular groove within the reference structure, the circular groove may extend around the vertex of the reference structure. The reference feature indicates a reference point substantially located at the vertex of the reference structure and within the range of the circular groove. The probe end may be in contact with the vertex of the reference structure (i.e., the reference point).

[0052] The reference feature portion may have dimensions approximately equal to the size of the probe end.

[0053] The reference feature may comprise a substantially circular groove formed within the reference structure, extending around the apex of the reference structure.

[0054] The reference structure may include a number of substantially circular grooves formed within the reference structure, each groove extending around the apex of the reference structure.

[0055] At least one of the standard structures may have a substantially spherical tip.

[0056] The spherical tip is surrounded by a virtually flat rim.

[0057] At least one of the reference structures has a surface having roughness features with a scale of 50 microns or less.

[0058] The roughness feature may include, for example, machined raised areas on the surface of the reference structure.

[0059] The device table may be capable of holding multiple devices under test.

[0060] The test system further comprises a kinematically restricted mount to which a device table is attached, the kinematically restricted mount being configured to restrict the movement of the device table in multiple degrees of freedom.

[0061] A kinematically restricted mount can, for example, limit the movement of the device table in six degrees of freedom.

[0062] The test system may further include a loading device capable of automatically loading the device under test and unloading it from the device table.

[0063] The test system further comprises a signal generator configured to generate a signal, guide the signal through at least one of the probe ends, and, in use, guide the signal to the device under test through the electrical contacts of the device under test; and a signal sampler configured to sample the signal passing through at least one of the probe ends, and, in use, sample the signal that is reflected at the device under test and passes through the probe end.

[0064] The signal generator may be configured to produce a broadband signal having frequency components in the range of 0.01 GHz to 10 THz.

[0065] A broadband signal may have only frequency components below approximately 1 THz. A broadband signal does not necessarily have frequency components across the entire range specified herein, but may simply have frequency components occupying a small area of ​​the range specified herein. For example, in some embodiments, a broadband signal may be limited to frequency components in the range of approximately 0.25 GHz to 200 GHz. Such a signal is considered an example of a broadband signal having frequency components in the range of 0.01 GHz to 10 THz.

[0066] The signal generator may include a pulsed radiation source, a first signal conversion device positioned to receive radiation pulses from the pulsed radiation source and configured to output signal pulses in response to irradiation from the pulsed radiation source, and a transmission line configuration configured to guide the signal pulses from the first signal conversion device through at least one of the probe ends.

[0067] The first signal conversion device may be configured to generate an electrical signal based on an optical signal. The first signal conversion device may, for example, include a photoconductive element. Alternatively, the first signal conversion device may include an electro-optical device.

[0068] The signal sampler may include a second signal converter that receives radiation pulses from a pulsed radiation source and, in response to irradiation from the pulsed radiation source, samples the received signal pulses in the second signal converter, and the transmission line configuration is configured to guide signal pulses reflected from or transmitted through the device under test and passing through at least one of the probe ends to the second signal converter.

[0069] The second signal conversion device may be configured to generate an electrical signal based on an optical signal. The second signal conversion device may include, for example, a photoconductive element. Alternatively, the second signal conversion device may include an electro-optical device. The pulsed radiation source may comprise a single radiation source or separate radiation sources for irradiating the first and second signal conversion devices. For example, the pulsed radiation source may comprise a first laser configured to irradiate the first signal conversion device and a second laser configured to irradiate the second signal conversion device.

[0070] According to a third aspect of the present invention, a test system for testing a device, the test system comprising: a pulsed radiation source configured to supply a generated radiation beam and a received radiation beam, wherein the generated radiation beam and the received radiation beam are pulsed radiation beams; a first signal conversion device positioned to receive pulses of the generated radiation beam and configured to output a signal pulse in response to receiving pulses of the generated radiation beam; a second signal conversion device positioned to receive pulses of the received radiation beam and configured to sample a signal pulse in response to receiving pulses of the received radiation beam; and a device that guides the signal pulse from the first signal conversion device to the device under test and transmits the signal pulse reflected from the device under test through the device under test. A test system is provided comprising: a transmission line configuration configured to lead to a second signal conversion device; and a direct-drive delay line positioned in the optical paths of a generated radiation beam and / or a received radiation beam, the delay line configured to introduce an optical delay between the generated radiation beam and the received radiation beam, such that pulses of the generated radiation beam are incident on the first signal conversion device at a different time than corresponding pulses of the received radiation beam incident on the second signal conversion device; wherein the delay line includes at least one reflector positioned in the optical paths of the generated radiation beam and / or the received radiation beam; and a synchronous linear motor configured to move the reflector, thereby changing the optical path length of the generated radiation beam and / or the received radiation beam, and thereby changing the optical delay between the generated radiation beam and the received radiation beam.

[0071] Directly driven delay lines, including those using synchronous linear motors, enable high-speed scanning of the delay line, allowing for rapid analysis of reflections and / or transmissions from the device under test at multiple different time delays relative to the input signal pulse. Directly driven delay lines can operate to scan delay times at speeds comparable to, for example, those of galvanometer-driven delay lines. However, directly driven delay lines can scan a larger delay time range than galvanometer-driven delay lines, thereby eliminating the need for separate high-speed and low-speed scanning delay lines. Overall acquisition time of measurements can be significantly improved compared to conventional configurations. For example, acquisition time can be approximately 60 times faster than that achievable with conventional configurations.

[0072] A synchronous linear motor can be a brushless motor.

[0073] The first and / or second signal conversion devices may be configured to generate an electrical signal based on an optical signal. The first and / or second signal conversion devices may, for example, include a photoconductive element. Alternatively, the first and / or second signal conversion devices may include an electro-optical device.

[0074] A pulsed radiation source may comprise a single radiation source and a beam splitter configured to split the output of the radiation source into a generated radiation beam and a received radiation beam. Alternatively, the pulsed radiation source may comprise separate radiation sources that emit the generated radiation beam and the received radiation beam, respectively. For example, the pulsed radiation source may include a first laser configured to emit a generated radiation beam and a second laser configured to emit a second radiation beam.

[0075] According to a fourth aspect of the present invention, a test system for testing a device, the test system comprising: a pulsed radiation source configured to supply a generated radiation beam and a received radiation beam, wherein the generated radiation beam and the received radiation beam are pulsed radiation beams; a first signal conversion device positioned to receive pulses of the generated radiation beam and configured to output a signal pulse in response to receiving pulses of the generated radiation beam; a second signal conversion device positioned to receive pulses of the received radiation beam and configured to sample a signal pulse in response to receiving pulses of the received radiation beam; and a signal pulse from the first signal conversion device A test system is provided, comprising: a transmission line configuration configured to guide signal pulses to a device under test and to guide signal pulses reflected from the device under test through the device under test to a second signal conversion device; a delay line including a movable stage to which the first reflector and the second reflector are attached, wherein movement of the movable stage in a first direction increases the optical path length of the generated radiation beam and decreases the optical path length of the received radiation beam, and movement of the movable stage in a second direction decreases the optical path length of the generated radiation beam and increases the optical path length of the received radiation beam.

[0076] This configuration means that the movement of the movable stage changes the optical path lengths of the generated radiation beam and the received radiation beam in opposite directions. As a result, moving the movable stage by a first distance introduces a difference in the optical path lengths of the generated radiation beam and the received radiation beam, which is at least twice the first distance. Therefore, a smaller movement of the movable stage is required to change the optical delay between the generated radiation beam and the received radiation beam by a given amount (compared to the prior art configuration). This favorably enables faster scanning of the optical delay. Thus, the acquisition time required to perform a given measurement can be reduced. The movable stage can be driven by a motor (e.g., a synchronous linear motor).

[0077] The first and / or second signal conversion devices may be configured to generate an electrical signal based on an optical signal. The first and / or second signal conversion devices may, for example, include a photoconductive element. Alternatively, the first and / or second signal conversion devices may include an electro-optical device.

[0078] A pulsed radiation source may comprise a single radiation source and a beam splitter configured to split the output of the radiation source into a generated radiation beam and a received radiation beam. Alternatively, the pulsed radiation source may comprise separate radiation sources that emit the generated radiation beam and the received radiation beam, respectively. For example, the pulsed radiation source may include a first laser configured to emit a generated radiation beam and a second laser configured to emit a second radiation beam.

[0079] A fifth aspect of the present invention provides a test system for testing a device, the test system comprising: a pulsed radiation source configured to supply a generated radiation beam and a received radiation beam, wherein the generated radiation beam and the received radiation beam are pulsed radiation beams; a first signal conversion device positioned to receive pulses of the generated radiation beam and configured to output a signal pulse in response to receiving pulses of the generated radiation beam; a second signal conversion device positioned to receive pulses of the received radiation beam and configured to sample a signal pulse in response to receiving pulses of the received radiation beam; a transmission line configuration configured to guide signal pulses from the first signal conversion device to the device under test and to guide signal pulses reflected from the device under test through the device under test to the second signal conversion device; a radiation sensor configured to detect the intensity of radiation pulses emitted from the pulsed radiation source; an attenuator positioned in the optical path of the radiation pulses emitted from the pulsed radiation source and configured to reduce the intensity of the radiation pulses by an adjustable amount; and a radiation feedback system including a controller configured to adjust the amount by which the attenuator reduces the intensity of the radiation pulses in response to a measurement of the intensity of the radiation pulses by the radiation sensor.

[0080] The controller can adjust the attenuator so that the average output of the radiation pulses, required over a period longer than a single pulse duration, remains substantially constant over time. The radiation pulses can be transmitted, for example, from a pulsed radiation source through an optical fiber to a radiation sensor. For example, a change in the coupling efficiency of the optical fiber results in a change in the intensity of the radiation received by the radiation detector, which is detected by the radiation sensor. The controller can respond to changes in intensity measured by the radiation detector, for example, to compensate for any changes in the coupling efficiency of the optical fiber.

[0081] The controller could be, for example, a proportional-integral-derivative (PID) controller.

[0082] The first and / or second signal conversion devices may be configured to generate an electrical signal based on an optical signal. The first and / or second signal conversion devices may, for example, include a photoconductive element. Alternatively, the first and / or second signal conversion devices may include an electro-optical device.

[0083] A pulsed radiation source may comprise a single radiation source and a beam splitter configured to split the output of the radiation source into a generated radiation beam and a received radiation beam. Alternatively, the pulsed radiation source may comprise separate radiation sources that emit the generated radiation beam and the received radiation beam, respectively. For example, the pulsed radiation source may include a first laser configured to emit a generated radiation beam and a second laser configured to emit a second radiation beam.

[0084] Features of different embodiments of the present invention can be combined with features of other embodiments of the present invention.

[0085] Embodiments of the present invention will be described here by reference only to the attached schematic diagrams. [Brief explanation of the drawing]

[0086] [Figure 1] This is a schematic diagram of an electronic device to be tested using a test system according to one embodiment of the present invention. [Figure 2] Figure 1 is a schematic diagram of a probe that may be used to establish electrical contact with the electronic device shown. [Figure 3A] This is a schematic diagram of an electronic device including a grounding plate. [Figure 3B] This is a schematic diagram of an electronic device including a grounding plate. [Figure 4] This is a schematic diagram of a portion of a test system that may form part of an embodiment of the present invention. [Figure 5] This is a schematic diagram of a portion of a test system that may form some of the alternative embodiments of the present invention. [Figure 6] This is a schematic diagram of a test system according to one embodiment of the present invention. [Figure 7] This is a schematic diagram of an embodiment of a loading device that may form part of the test system shown in Figure 6. [Figure 8] This is a schematic diagram of a portion of an electronic device shown in cross-section. [Figure 9A] Figure 6 is a schematic diagram of an embodiment of a profile determination system that may form part of the test system. [Figure 9B] Figure 6 is a schematic diagram of an embodiment of a profile determination system that may form part of the test system. [Figure 10] Figure 6 is a schematic diagram of a device table that may form part of the test system. [Figure 11] Figures 11A-11C are schematic diagrams of reference structures that may form part of the device table in Figure 10. [Figure 12] Figure 6 is a schematic diagram of an embodiment of a mount that may form part of the test system. [Figure 13] This is a schematic diagram of a part of a test system according to one embodiment of the present invention. [Figure 14] This is a schematic diagram of a delay line configuration that may form part of a test system according to one embodiment of the present invention. [Figure 15] This is a schematic diagram of a radiation feedback system that can form part of a test system according to one embodiment of the present invention. [Modes for carrying out the invention]

[0087] Figure 1 is a schematic diagram of an electronic device 1 that can be tested using a test system according to one embodiment of the present invention. The electronic device 1 may be called the device under test (DUT). The DUT 1 comprises a plurality of electrical contacts 3. The plurality of electrical contacts 3 may include, for example, a ball grid array (BGA), a land grid array (LGA), or a pin grid array (PGA). The DUT can be tested by simultaneously making electrical contact between at least two of the electrical contacts 3 and a probe.

[0088] Figure 2 is a schematic diagram of a probe 5 that may be used to establish electrical contact with the electrical contacts 3 of the DUT 1. The probe 5 includes a coaxial cable portion 7 that terminates at a first probe end 13 and a second probe end 15. The coaxial cable portion 7 comprises an inner conductor 9 surrounded by an outer conductor 11 arranged in a coaxial transmission line configuration (the dotted line used to indicate the inner conductor 9 shows that the inner conductor 9 is surrounded by the outer conductor 11). The inner conductor 9 is electrically insulated from the outer conductor 11. Towards the end of the probe 7, the inner transmission 9 extends outside the outer conductor 11 and tapers to form the first probe end 13. The second probe end 15 extends outside the outer conductor 11 and is formed of a fin electrically coupled to the outer conductor 11.

[0089] To test DUT1, the first probe end 13 can contact the first electrical contact 3 on DUT1, and the second probe end 15 can contact the second electrical contact 3 on DUT1. The inner conductor 9 and the first probe end 13 may be used to input a signal to DUT1 and can therefore be considered to carry live current. The second probe end 15 and the outer conductor 11 may be used to conduct ground current. Alternatively, the inner conductor 9 can conduct ground current and the outer conductor 11 can conduct live current.

[0090] In some embodiments, a probe may have three or more probe ends. For example, a probe may have three probe ends. A probe with three probe ends may have one probe end that conducts active current and two probe ends that each conduct ground current. Such a configuration may be called a ground-signal-ground probe configuration.

[0091] In some embodiments, the DUT1 may be provided with a grounding plate that can be connected to ground. Figures 3A and 3B are schematic diagrams of the DUT1 including the grounding plate 2. Figure 3A shows the grounding plate 2 separated from the rest of the DUT1, and Figure 3B shows the grounding plate 2 in contact with the rest of the DUT1. The grounding plate 2 includes an opening 4 through which electrical contacts 3 can be accessed.

[0092] The grounding plate 2 may have a laminated structure. For example, the grounding plate 2 may comprise a conductive upper layer and an insulating lower layer. The conductive upper layer may include, for example, gold-plated copper. The insulating lower layer may include, for example, a polymer (e.g., polytetrafluoroethylene (PTFE)). The lower insulating layer acts to prevent electrical contact between the contact 3 and the conductive upper layer.

[0093] As shown in Figure 3B, the DUT1 can be tested by bringing the first probe end 13 of the probe 7 into contact with the electrical contact 3 and the second probe end 15 into contact with the grounding plate 2. The grounding plate 2 may be an element separate from the device to be tested and may be placed only on the device in order to test the device. For example, the grounding plate 2 may be placed on the device to test an electrical contact that does not have a suitable adjacent contact to which the second probe end is connected.

[0094] Although the grounding plate may be a separate element from the device to be tested, for the purposes of this description, the grounding plate 2 positioned on the device is considered to form part of the device under test DUT1. Furthermore, the grounding plate 2 is considered to be an example of an electrical contact on the DUT1 that the probe ends 13, 15 can contact. In this specification, any reference to contacting an electrical contact 3 on the DUT1 includes contacting the grounding plate 2 positioned on the device.

[0095] Figure 4 is a schematic diagram of a portion of a test system 15 that may form part of an embodiment of the present invention. The test system 15 comprises a signal generator 17 and a signal sampler 19. The signal generator 17 can generate a broadband signal having frequency components in the range of, for example, 0.01 GHz to 10 THz. In some embodiments, the signal generator can generate a broadband signal having frequency components in the range of 0.25 GHz to 200 GHz. A broadband signal does not necessarily have frequency components across the entire range specified herein, but may simply have frequency components occupying a small area of ​​the range specified herein. For example, a broadband signal having frequency components in the range of about 0.25 GHz to 200 GHz (but having substantial frequency components at frequencies higher than, for example, about 200 GHz) can be considered an example of a broadband signal having frequency components in the range of 0.01 GHz to 10 THz.

[0096] The signal generator 17 generates a signal for input to the DUT1. The signal sampler 19 receives and analyzes the signal reflected from the DUT1. Both the signal generator 17 and the signal sampler 19 are connected to the probe 7 via the transmission line 21. The probe 7 may be similar to the probe 7 described above with reference to Figure 2, for example, and will not be described in further detail with reference to Figure 4. Similar reference numbers in Figures 2 and 4 indicate similar features of the probe 7.

[0097] The first probe end 13 of probe 7 is connected to the first electrical contact 3 on DUT1. The second probe end 15 is connected to the second electrical contact 3 on DUT1. For simplicity of explanation, only two electrical contacts 3 are shown on DUT1 in Figure 4. However, it will be understood that DUT1 may have three or more electrical contacts 3.

[0098] The internal conductor 9 of the probe 7, which is electrically connected to the first probe end 13, is connected to a transmission line 21 that transmits signals from the signal generator 17 to the signal sampler 19. Thus, the signal generated by the signal generator 17 is transmitted to the electrical contact 3 of the DUT 1 through the transmission line 21, the internal conductor 9 of the probe 7, and the first probe end 13. Any signals reflected in the DUT 1 can be transmitted to the signal sampler 19 for analysis through the first probe end 13, the internal conductor 9 of the probe 7, and the transmission line 21.

[0099] The signal generator 17 includes a bias element 16 and a first photoconductive element 23. The signal sampler 19 includes a measuring device 20 and a second photoconductive element 25. The first and second photoconductive elements are conductive in response to irradiation by radiation and substantially non-conductive when not irradiated by radiation. The first and second photoconductive elements 23 and 25 can be selectively irradiated by radiation to generate a signal in the first photoconductive element 23 and to sample the signal in the second photoconductive element 25. The signal generator 17 and the signal sampler 19 can be considered to form a sampling module 18 that is operable to input signal pulses to the DUT 1 through the probe 7 and receive signal reflections from the DUT 1.

[0100] The test system 15 further comprises a radiation source 27. The radiation source 27 emits radiation pulses in the form of a pulsed radiation beam 29. The radiation source 27 may include, for example, a laser. The radiation beam is incident on a beam splitter 31, which splits the pulsed radiation beam 29 into a generating beam 33 containing generating pulses and a receiving beam 35 containing receiving pulses. The generating beam 33 is directed to incident on a first photoconductive element 23, and the receiving beam 35 is directed to incident on a second photoconductive element 25.

[0101] The pulse generation beam 33 generates a signal pulse in the first photoconductive element 23 and inputs it to the DUT 1. The bias element 16 applies a potential to the first photoconductive element 23. For example, the bias element 16 may apply a DC potential or an AC potential (for example, having a frequency of about 30 kHz) to the first photoconductive element 23. When a radiation pulse is incident on the first photoconductive element 23, a signal pulse is generated in the first photoconductive element 23 due to the combination of the bias element 16 and the irradiation of the first photoconductive element 23. Therefore, the first photoconductive element acts to generate an electrical signal based on the optical signal.

[0102] The pulsed receiving beam 35 acts to sample the electrical signal received at the second photoconductive element 25 (when the second photoconductive element 25 receives a radiation pulse) at a selected time. The signal sampled at the second photoconductive element 25 is measured by the measuring device 20. It can be considered that the second photoconductive element 25 generates an electrical signal (which is measured by the measuring device 20) based on the optical signal (supplied by the receiving beam 35). The electrical signal generated at the second photoconductive element 25 is similarly based on the signal reflected from the DUT1. This process can be called signal sampling.

[0103] The optical path of the receiving beam 35 to the second photoconductive element 25 includes a delay line 37 configured to introduce an optical delay between the generated pulse of the generated beam 33 and the received pulse of the receiving beam 35. The optical delay introduced by the delay line 37 causes the generated pulse to be incident on the first photoconductive element 23 at a different time than the corresponding received pulse incident on the second photoconductive element 25. As a result, there is a delay between the signal pulse sent to the DUT1 (from the signal generator 17) and the reflected signal sampled by the second photoconductive element 25 and received by the measuring device 20.

[0104] The delay time between the input signal pulse and the reflection sampled by the signal sampler 19 can be adjusted to analyze reflections from DUT1 at different delay times after the pulse is input to DUT1. The delay line 37 includes a movable stage 39 on which a reflector is mounted in the optical path of the received beam 35. Movement of the movable stage 39 (indicated by a two-headed arrow in Figure 4) changes the optical path length of the received beam 35 and thus changes the optical delay between the generated pulse 33 incident on the first photoconductive element 23 and the received pulse incident on the second photoconductive element 25. The movable stage 39 can be scanned, for example, to analyze reflections from DUT1 at different delay times.

[0105] It should be understood that the components shown in Figure 4 are not shown to a constant scale. Test system 15 may include components different from those illustrated in Figure 4 and described above, and / or may include additional components beyond those described and illustrated. Details of other embodiments of the test system are given in US20140021963, which is incorporated herein by reference in its entirety. Any of the features disclosed in US20140021963 may be used in conjunction with the test system described herein.

[0106] As described above, the first photoconductive element 23 and the second photoconductive element 25 generate an electrical signal based on an optical signal. The first and second photoconductive elements 23 and 25 can be considered examples of signal conversion devices. In some embodiments, signal conversion devices other than photoconductive elements may be used. For example, the first and / or second photoconductive elements 23 and 25 may be replaced by other forms of signal conversion devices.

[0107] Alternative signal conversion devices that may form part of the embodiments of the present invention may be electro-optic devices such as electro-optic crystals. An electro-optic crystal forming part of a signal generator may be configured to receive a polarized radiation beam (e.g., a generated beam 33) and generate an electrical signal based on the polarized radiation beam.

[0108] An electro-optic crystal forming part of a signal sampler may be configured to change its optical properties in response to exposure to an electric field. For example, the birefringence of the crystal may change in response to exposure to an electric field. An electrical signal incident on the electro-optic crystal from DUT1 exposes the crystal to an electric field. A receiving beam 35 may be guided to be incident on the electro-optic crystal, and the receiving beam 35 transmitted by the crystal may be detected by one or more sensors. A change in the optical properties of the crystal (e.g., birefringence) induces a change in the receiving beam 35 transmitted by the crystal, which may be detected by one or more sensors. For example, a signal from DUT1 may act to change the polarization state and / or amplitude of the receiving beam 35 transmitted by the crystal. For example, a change in polarization state and / or amplitude may be measured using, for example, a polarizing optical element and one or more photodiode sensors. This may result in a measurement signal proportional to the signal received from DUT1.

[0109] Similar to the operation of the photoconductive element described above, the electro-optic crystal can be used with pulse-generating beam and pulse-receiving beam 33, 35 to generate signal pulses and sample reflected signals at a selected time. An optical delay can be introduced between the generating beam 33 and the receiving beam 35, allowing reflections received at different delay times to be analyzed (as described above with reference to embodiments including the photoconductive element).

[0110] In some embodiments, different types of signal conversion devices may be used in the signal generator 17 and the signal sampler 19. For example, a photoconductive element may be used in the signal generator 17, and an electro-optic crystal may be used in the signal sampler 19.

[0111] While an embodiment has been described above in which a radiation beam 29 is emitted from a radiation source 27 and split into a generated beam 33 and a received beam 35, in some embodiments, separate radiation sources may be used to generate the generated beam and the received beam. For example, in some embodiments, a dual-laser system including two synchronized lasers may be used. The lasers may be synchronized in a controllable manner so that the optical delay between the radiation beams emitted from the two lasers is controlled and adjusted (e.g., electronically). In such embodiments, the synchronization between the lasers may be adjusted to analyze signals received at different delay times (as described above with reference to the delay line 37). Since the function of the delay line can be replaced by adjusting the synchronization between the lasers, embodiments including a dual-laser system may not include a delay line. However, in some embodiments, a delay line may still be used with a dual-laser system.

[0112] In embodiments including two or more radiation sources (e.g., a dual laser system), it may be conceivable that the multiple radiation sources combine to form a pulsed radiation source. The pulsed radiation sources described herein are intended to include a single radiation source or multiple radiation sources, such as a dual laser system. In embodiments in which the pulsed radiation source includes a single radiation source, the pulsed radiation source may further include a beam splitter configured to split the radiation beam into a generating radiation beam and a receiving radiation beam.

[0113] In some embodiments, the DUT1 may be tested using two or more probes 7 and two or more sampling modules 18. Figure 5 is a schematic diagram of a portion of a test system 15' including a first sampling module 18a and a second sampling module 18b. The first sampling module 18a is connected to a first probe 7a, and the second sampling module 18b is connected to a second probe 7b. Both the first and second probes 7a and 7b are in contact with electrical contacts 3 on the DUT1.

[0114] The first and second sampling modules 18a and 18b are supplied with radiation emitted from a radiation source 27 (e.g., a laser). The radiation source 27 emits a radiation beam 29, which is split by a beam splitter 31 into a generated beam 33 and a received beam 35. The received beam 35 is led to a delay line 37 that is operable to introduce an optical delay between the generated beam 33 and the received beam 35. The generated beam 33 is split by the beam splitter 31 into first and second parts 33a and 33b. The received beam 35 is split by the beam splitter 31 into first and second parts 35a and 35b. The first part 33a of the generated beam and the first and second parts 35a of the received beam are supplied to the first sampling module 18a. The generated beam and the first and second parts of the received beam are coupled to an optical fiber 32 by a fiber coupler 34 and via a mirror 38. The second portion 33b of the generated beam and the second portion 35b of the received beam are supplied to the second sampling module 18b.

[0115] In the configuration shown in Figure 5, the first and second sampling modules 18a and 18b are operated using a common generating beam 33 and receiving beam 35. In this configuration, the sampling modules 18a and 18b can measure the signal transmitted between the first and second probes 9A and 9B through the DUT1, in addition to the signal reflected at the DUT1. The reflected signal can be separated from the transmitted signal by selectively turning off pulse generation alternately in each sampling module 18a and 18b. For example, the first sampling module 18a can initially generate a signal pulse. The transmission of the pulse can be measured by the second sampling module 18b, and the reflection of the pulse can be measured by the first sampling module 18a. Subsequently, the second sampling module 18b can generate a signal pulse. The transmission of the pulse can be measured by the first sampling module 18a, and the reflection of the pulse can be measured by the second sampling module 18b.

[0116] The measurements described above can be used to form a 2x2 matrix S describing the coupling between the two electrical contacts, and are given by equation (1) below.

[0117]

number

[0118] element S 11 This represents the signal inserted at the first electrical contact and reflected back to the first electrical contact. Element S 22 This represents the signal inserted at the second electrical contact and reflected back to the second electrical contact. Element S 12 This represents a signal inserted at the first electrical contact and transmitted to the second electrical contact. Element S 21 This represents the signal inserted at the second electrical contact and transmitted to the first electrical contact. The matrix S may be called the S-parameter measurement or scattering matrix of DUT1.

[0119] In some embodiments, the test system may comprise three or more sampling modules and may simultaneously test DUT1 through two or more electrical contacts. Generally, an N×N S-parameter matrix can be derived by sampling DUT1 through N electrical contacts.

[0120] The embodiment shown in Figure 5 includes a delay line 37, but it will be understood that the delay between the generating beam 33 and the receiving beam 35 can instead be introduced by using a dual laser system, as described above. The first laser emits the generating beam 33, and the second laser emits the receiving beam 35. The first and second lasers can be synchronized, and the synchronization between the lasers can be controlled to control the optical delay between the generating beam and the receiving beam.

[0121] As described above, DUT1 can be tested through one or more probes 7 that are brought into contact with one or more electrical contacts using various different methods. A signal is input to DUT1, and the reflection and / or transmission of the signal by DUT1 can be measured. The embodiments described below focus on measuring the signal reflected by DUT1. However, it will be understood that similar principles apply to the measurement of transmitted signals. Therefore, the following description can also be applied to the measurement of transmitted signals, as opposed to the measurement of reflected signals.

[0122] It may be desirable to test the DUT1 through multiple different electrical contacts 3. This can be achieved by moving the probe 7 and / or DUT1 so that the probe ends 13, 15 contact different electrical contacts 3. At each position of the probe 7 and DUT1, a signal pulse can be input to the DUT1 through the probe 7, and the signal reflection from the DUT1 can be analyzed at different delay times.

[0123] It is desirable to provide an automatic or semi-automatic test system that automatically moves the probe and / or DUT1 so that the probe tip contacts different electrical contacts and DUT1 can be tested through different electrical contacts. Providing an automatic or semi-automatic test system can significantly reduce the time required to test DUT1 (compared to, for example, manually contacting the electrical contacts with the probe). An automatic or semi-automatic test system may enable DUT1 to be rapidly tested through multiple electrical contacts 3. An automatic or semi-automatic test system may enable multiple DUT1 to be rapidly tested in succession.

[0124] Figure 6 is a schematic diagram of a test system 101 according to one embodiment of the present invention. The test system comprises a device table 103 operable to hold at least one device 1. In some embodiments, the device table 103 may be operable to hold multiple devices 1. The device table 103 is located on a mount 104. The mount 104 is located on a moving stage 106. Multiple devices 1 may be held, for example, in trays 105. Multiple trays 105 of devices 1 may be held in a tray holder 107. The trays 105 can be unloaded (removed) from the tray holder 107 to test one or more devices held on the trays 105 (as shown in Figure 6).

[0125] The test system 101 further includes a loading device 109 that is capable of automatically loading device 1 and unloading it from the device table 103. For example, the loading device 109 can move device 1 from the tray 105 and load device 1 onto the device table 103. After device 1 has been tested while held on the device table 103, device 1 can be unloaded from the device table 103 and returned to the tray 105.

[0126] Figure 7 is a schematic diagram of one embodiment of the loading device 109. The loading device 109 comprises a robot having a first arm 111, a second arm 113, and an actuator 115 positioned at the end of the second arm 113. The first arm 111, the second arm 113, and the actuator 115 are rotatable around a joint 117. Rotating the first arm 111, the second arm 113, and / or the actuator 115 around the joint 117 allows the actuator 115 to move between components. The loading device 109 has an outer reach indicated by a dashed line 119.

[0127] Figure 7 also shows the tray 105, the first device table 103a, and the second device table 103b located on the mount 104. The loading device 109 is operable to load device 1 from tray 105 onto device table 103. In the depiction shown in Figure 7, the loading device 109 is in the process of loading device 1 from tray 105 onto device table 103a. The loading device 109 can move device 1 by moving actuator 115 to a position to pick up device 1. Next, actuator 115 clasps device 1, and device 1 may be moved to a different position by actuator 115 to unload.

[0128] In the embodiment shown in Figure 7, device tables 103a and 130b are operable to hold six devices each. Once device 1 is loaded into device table 103, device table 103 can be loaded onto mount 104 on which device 1 can be tested. Device table 103 can be moved onto mount 104 and loaded, for example, by a loading device 109. As shown in Figure 7, a device can be loaded into the first device table 103a, while the second device table 103b is located on mount 104 and device 1 on the second device table 103b is tested. This can improve the throughput of the test system 101. The throughput of the test system can be thought of as the number of devices tested per unit time.

[0129] Returning to Figure 6, the test system 101 shown in Figure 6 further comprises a pair of probes 7. Although not shown in detail in Figure 6, the probes 7 may be similar to the embodiments of the probes described above with reference to Figure 6. Each probe is connected to a sampling module 18. The sampling module 18 is operable to input signal pulses to the DUT 1 through the probes 7 and to receive signal reflections from the DUT 1, as described above with reference to Figure 4. The sampling module 18 in the embodiment of Figure 6 may be similar to the sampling module 18 described above with reference to Figure 4 and may have any of the features of the sampling modules described herein.

[0130] In the embodiment shown in Figure 6, the sampling module is coupled to an optical fiber 121, the other end of which is coupled to a radiation source 27. As described above with reference to Figure 4, the radiation source 27 emits pulses of radiation that can be directed to incident on a photoconductive element forming part of the sampling module 18. Although not shown in Figure 6, the test system 101 may further include one or more delay lines configured to introduce optical delays between the radiation pulses emitted from the radiation source 27. The operation of the radiation source 27 and the sampling module 18 will not be described in further detail with reference to Figure 6. As described above, alternative embodiments of the sampling module and / or radiation source may be used.

[0131] The probe 7 can be brought into contact with electrical contacts 3 (not shown in Figure 6) on the DUT 1 through probe ends 13, 15 (not shown in Figure 6) of the probe 7. The test system 101 includes a movable mechanism 122 that can move one or both of the device table 103 and the probe 7 to bring the probe ends 13, 15 into contact with at least two electrical contacts 3 on the DUT 1. The movable mechanism can take various different forms and may include multiple components that are not shown in detail, so it is schematically shown only as box 122 in Figure 6.

[0132] The moving mechanism 122 may comprise one or more actuators configured to move components of the test system 101, for example. For example, one or more actuators may be configured to move the probe 7, causing the probe ends 13, 15 on the probe 7 to contact the electrical contacts 3 on the DUT 1. In addition to or instead of this, one or more actuators may be configured to directly move the device table 103 on which the DUT 1 is located. In addition to or instead of this, one or more actuators may be configured to move the mount 104 on which the device table 103 holding the DUT 1 is located. In addition to or instead of this, one or more actuators may be configured to move the moving stage 106 on which the mount 104 is located. The moving mechanism may be operable to translate and / or rotate one or more components (e.g., the device table 103 and / or the probe 7). The moving mechanism may be operable to adjust the position and / or orientation of one or more components (e.g., the device table 103 and / or the probe 7).

[0133] It is understood that, in order to bring the probe ends 13 and 15 of probe 7 into contact with the electrical contacts 3 of DUT1, it is desirable to know the position of the electrical contacts 3 to be contacted relative to the positions of the probe ends 13 and 15. Knowing these positions allows for the determination of the necessary movement of the device table 103 in which probe 7 and / or DUT1 are positioned in order to make contact with the electrical contacts. However, the position, size, and / or shape of the electrical contacts 3 on DUT1 may differ for different devices and cannot be known before testing the device.

[0134] Figure 8 is a schematic cross-sectional view of a portion of the DUT1. The DUT1 includes multiple electrical contacts 3 (shown as ball-type electrical contacts in Figure 8). Figure 8 also shows a probe 7 that may be used to make contact with the electrical contacts 3. The probe 7 shown in Figure 8 is the same as the probe 7 described above with reference to Figure 2, and will not be described in further detail here.

[0135] As can be seen in Figure 8, the electrical contacts 3 are not all the same size and shape. Furthermore, the pitch 123 between adjacent electrical contacts 3 is not consistent with respect to each of the electrical contacts 3. The pitch 123 between adjacent contacts 3 does not have to coincide with the pitch 125 between the probe ends 13, 15 of the probe 7. Finding the position and orientation of the probe 7 relative to the DUT1 so that the probe ends 13, 15 contact two electrical contacts of the DUT1 simultaneously may not be straightforward. For example, the probe 7 may be tilted relative to the DUT1 in order to contact two electrical contacts 3 simultaneously. The angle at which the probe 7 is tilted relative to the DUT1 may differ when contacting different electrical contacts 3.

[0136] To bring the probe ends 13 and 15 into contact with the electrical contacts of the DUT1, the configuration of the moving mechanism 122 that achieves contact can be determined. The moving mechanism 122 is operable to move one or both of the device table 103 and the probe 7 to adopt the determined configuration in which the probe ends 13 and 15 of the probe 7 are in contact with the electrical contacts 3 on the DUT1. References to the movement of the device table 103 in this specification may include the direct movement of the device table 103 or the movement of another component on which the device table 103 is located. For example, the movement of the mount 104 on which the device table 103 is located is one example of the movement of the device table 103. Similarly, the movement of the moving stage 106 on which the device table 103 is located is a further example of the movement of the device table 103.

[0137] To determine the configuration of the moving mechanism 122 that brings the probe ends 13 and 15 of the probe 7 into contact with the electrical contacts 3 of the DUT 1, it is desirable to obtain knowledge of the position, size, and / or shape of the electrical contacts of the DUT 1. Referring again to Figure 6, the test system 101 further comprises a profile determination system 127. The profile determination system 127 is configured to determine the profile of the electrical contacts of the device. For example, the profile determination system may be configured to determine the three-dimensional profile of the electrical contacts of the device. The determined profile of the electrical contacts is then used to determine the configuration of the moving mechanism 122 that brings the probe ends 13 and 15 of the probe 7 into contact with the electrical contacts 3 of the DUT 1.

[0138] An embodiment of the profile determination system 127 is shown in more detail in Figure 9. Figure 9A is a schematic diagram of one embodiment of the profile determination system 127 viewed from the side. Figure 9B is a schematic diagram of device 1 viewed from above, and device 1 is irradiated by a radiation strip by the profile determination system 127.

[0139] The profile determination system 127 comprises a radiation source 129, a radiation sensor 131, and a controller 133. The radiation source 129 is configured to irradiate at least a portion of the device under test with radiation 135. In the embodiment shown in Figure 9, the radiation source 129 is configured to irradiate a strip of device 1 with the radiation strip 135. The radiation sensor 131 is configured to detect radiation scattered from device 1. For example, the radiation sensor 131 may detect radiation scattered from an electrical contact 3 on device 1. The controller is configured to determine the profile (e.g., a three-dimensional profile) of the electrical contact of device 1 from the detected scattered radiation.

[0140] The radiation source 129 may include, for example, one or more light-emitting diodes (LEDs). In some embodiments, the radiation source 129 may include a laser. However, lasers typically emit coherent radiation. Coherent radiation scattered from device 1 may form interference patterns (e.g., speckle patterns) that can be seen by the radiation sensor 131, and may result in measurements generated by the radiation sensor 131. Radiation emitted from LEDs is typically less coherent than radiation emitted from lasers. As a result, the use of one or more LEDs advantageously reduces the impact of any interference effects on measurements generated by the radiation sensor 131.

[0141] The radiation sensor 131 may include, for example, a camera. In the embodiment shown in Figure 9, the radiation sensor 131 is oriented at an oblique angle α with respect to the propagation direction of the radiation 135 emitted from the radiation source 129. The radiation sensor 131 is positioned such that different parts of the device 1 having different heights appear at different positions within the field of view of the radiation sensor 131. The controller 133 can determine the position on the device 1 from which the scattered radiation is scattered, based on the position within the field of view of the radiation sensor where the scattered radiation appears. This may allow the position and / or shape of the scattering surface of the device under test to be determined.

[0142] As described above, in the embodiment shown in Figure 9, the radiation source 129 is configured to irradiate a strip of device 1 with a radiation strip 135. The radiation sensor 131 is configured to detect radiation scattered from device 1 located within the radiation strip (for example, from the electrical contacts of device 1). The controller 133 is configured to determine the height of a point on device 1 located within the irradiated strip of device 1.

[0143] The radiation strip 135 can be scanned on device 1, as indicated by the double-headed arrow in Figure 9B. For example, the moving mechanism 122 can move one or both of the device table 103 and the radiation source 129 on which device 1 is located to scan the radiation strip 135 on device 1. At each position of the radiation strip 135 on device 1, the controller 133 determines the height of the point of device 1 located within the radiation strip 135. The controller 133 combines the determined heights of device 1 at different positions on the radiation strip 135 to determine the three-dimensional profile of device 1. The profile of device 1 includes the profile of the electrical contacts 3 on device 1.

[0144] In some embodiments, the radiation source 129 and the radiation sensor 131 may be arranged such that specular reflection from the electrical contact 3 is received by the radiation sensor 131. This can increase the detection signal received by the radiation sensor 131 and, therefore, improve the accuracy of profiling. Such embodiments are particularly applicable to profiling devices including a land grid array (LGA) of electrical contacts 3. The electrical contacts 3 forming the land grid array may have a relatively small height compared to other forms of electrical contacts. Therefore, profiling the LGA can be difficult to detect. Detecting specular reflection from the LGA can improve the accuracy of profiling the LGA.

[0145] In some embodiments, the profiling system 127 may include a plurality of radiation sources 129. A first radiation source may be directed so that specular reflection from an electrical contact 3 is received by a radiation sensor 131. The first radiation source may be used to profile a device 1 that includes an LGA. A second radiation source may be directed so that diffusely scattered radiation, rather than specular reflection, is received by a radiation sensor. The second radiation source may be used to profile a device that does not include an LGA.

[0146] In other embodiments, the profile determination system 127 may determine the profile of the electrical contacts 3 on the DUT 1 by means other than those described above with reference to Figure 9. For example, the profile determination system 127 may include a camera that acquires an image of the DUT 1 from above. Image processing may be performed on the acquired image to detect the position of the electrical contacts 3 in the image. In some embodiments, two-dimensional information regarding the position of the electrical contacts 3 may be combined with information acquired from one or more additional sensors configured to provide information regarding the height of the DUT 1.

[0147] In some embodiments, the height of an electrical contact 3 on the DUT1 can be determined by irradiating the electrical contact 3 with a radiation beam and measuring the return time of the radiation reflected from the electrical contact 3. The return time can be used to determine the height of the electrical contact 3. For example, the profile determination system 127 may include a laser configured to irradiate a portion of the DUT1 with a laser beam and a radiation sensor positioned to measure the return time of the laser radiation reflected from the DUT1. A controller can determine the height of a point on the DUT1 based on the return time. The laser and / or DUT1 may be moved to irradiate different locations on the DUT1 and determine the height of the DUT1 at those different locations. The determined heights of the DUT1 at different locations on the DUT1 can be combined to form a profile of the DUT1 that includes the profile of the electrical contact 3 on the DUT1.

[0148] In some embodiments, information regarding the height of the DUT1 at different locations (e.g., acquired using a laser as described above) can be combined with information derived from acquired images of the DUT1. For example, an image of the DUT1 from which the positions of electrical contacts 3 on the DUT1 can be derived can be combined with height information to determine the profile of electrical contacts 3 on the DUT1.

[0149] While embodiments have been described in which the three-dimensional profile of the electrical contacts of DUT1 can be determined, in some embodiments, a two-dimensional profile may suffice. For example, if DUT1 comprises multiple electrical contacts 3 arranged in a line, it may suffice to determine the height of the electrical contacts 3 as a function of their position along the line, thereby determining the two-dimensional profile of the electrical contacts 3. In embodiments in which DUT1 includes a more complex arrangement of electrical contacts 3, it is desirable to determine the three-dimensional profile of the electrical contacts 3.

[0150] To determine the configuration of the moving mechanism 122 that brings the probe ends 13 and 15 of the probe 7 into contact with the electrical contacts 3 of the DUT1, it is desirable to know the position of the profile of the DUT1 relative to the position of the probe 7. In some embodiments, this can be achieved by determining the position of the profile of the DUT1 relative to the device table 103 in which the DUT1 is held. The position of the probe 7 relative to the device table 103 can be determined in a similar manner, thereby providing the position of the profile of the DUT1 relative to the position of the probe 7.

[0151] In this specification, when referring to the position of an element relative to the position of another element, this shall include the relative orientation of the two elements. For example, determining the position of probe 7 relative to device table 103 may include determining the relative orientation of probe 7 and device table 103.

[0152] Figure 10 is a schematic diagram of the device table 103. Figure 10 also shows the coordinate system used to describe the position and orientation of the device table 103. The device table 103 can be translated in the x, y, and z directions, and can be rotated by an azimuth angle φ with respect to the x-axis and a polar angle θ with respect to the z-axis.

[0153] The device table 103 includes device mounting positions 137 on which device 1 can be mounted. In the embodiment shown in Figure 10, the device table 103 includes six device mounting positions 137. In other embodiments, the device table 103 may include more than six or fewer device mounting positions 137.

[0154] Device 1 can be held in a predetermined position on the device table 103 by vacuum clamping it to the device table 103. In the embodiment shown in Figure 10, the device mounting position 137 is provided with a vacuum port 139 that can be operated to apply vacuum to the underside of the device in order to clamp device 1 to the device table 103.

[0155] The device table 103 shown in Figure 10 includes a gripping position 141. The gripping position 141 provides a contact point from which the device table 103 can be gripped in order to hold and move the device table 103. For example, the actuator 115 of the loading device 109 shown in Figure 7 can grip the device table 103 at the gripping position 141.

[0156] The device table 103 further includes a shorting pad 143, which provides a location where components can be shorted together. For example, both of two probe ends 13 and 15 may be brought into contact with the shorting pad 143, resulting in a short circuit between the two probe ends 13 and 15. This may allow one or more reference measurements to be obtained. For example, a measurement of signal reflection from the shorted probe ends may be obtained as a reference measurement. If the probe ends 13 and 15 are not shorted together, another reference measurement may be obtained. The shorting pad 143 may be gold-plated, for example.

[0157] Mounting points 145 are provided on the underside of the device table 103. Mounting points 145 may be configured to interface with a mount 104 on which the device table 103 is mounted. The mount 104 may include kinematically restricted mounts. Embodiments of the mount 104 on which the device table 103 may be mounted are described in further detail below with reference to Figure 12.

[0158] The device table 103 further includes a reference structure 147. The reference structure 147 may, for example, be fitted into a hole in the device table 103. The reference structure 147 provides a reference point at a known location on the device table 103. The reference structure 147 may provide a reference position on the device table 103 in which the profile of the electrical contacts 3 on the DUT 1 can be measured in comparison. For example, a profile determination system 127 may determine the profile of the device table 103, which may include the profile of the electrical contacts 3 on the DUT 1 placed on the device table, and similarly, the profile of the reference structure 147 on the device table 103. The reference structure 147 may be identified in the determined profile. Since the reference structure 147 may be placed at a known location on the device table 103, identifying the reference structure 147 in the determined profile of the device table 103 may enable the determination of the position of the electrical contacts 3 on the DUT 1 placed on the device table 103. The determined position of the electrical contact 3 on the device table 103 may allow for the determination of the position where the probe 7 should be moved relative to the device table 103 in order to make contact with the electrical contact 3.

[0159] The reference structure 147 may extend outside the device table 103 (as shown in Figure 10). In an alternative embodiment, the reference structure 147 may extend inside the device table 103 (for example, the reference structure may be embedded within the device table 103). In the embodiment shown in Figure 10, the reference structure 147 is located at different vertical levels (i.e., different positions on the z-axis shown in Figure 10) with respect to the level on which the device 1 is supported. The device mounting position 137 configured to support the device 1 may be located substantially within the support plane. In the embodiment shown in Figure 10, the reference structure 147 extends from a plane substantially parallel to the support plane. In other embodiments, the reference structure 147 may extend from the support plane. The reference structure 147 may extend in a direction perpendicular to the support plane (as shown in Figure 10).

[0160] At least two of the reference structures 147 may extend outside or inside the device table 103 by different distances. For example, in some embodiments, all reference structures may extend outside or inside the device table 103 by different distances. The distance by which a reference structure 147 extends outside or inside the device table 103 may be called the height of the reference structure 147. The distance by which a reference structure 147 extends outside or inside the device table may be the distance perpendicular to the support surface. In the embodiment of Figure 10, the distance by which a reference structure 147 extends outside the device table 103 may be the distance by which the reference structure 147 extends from a plane substantially parallel to the support surface. In embodiments where the reference structure 147 extends from the support surface, the distance may be the distance by which the reference structure 147 extends from the support surface.

[0161] Reference structures 147 extending outside or inside the device table by different distances advantageously improve the accuracy with which the position of a feature (e.g., an electrical contact 3 on the DUT1) can be determined relative to the reference structure 147. In some embodiments, the reference structures may all extend approximately the same distance outside or inside the device table 103. However, in such embodiments, accurately making contact with the electrical contacts 3 located at different heights may depend on the accuracy and linearity of the profile determination system 127. By positioning the reference structures 147 at different heights (i.e., extending different distances outside or inside the device table 103), references at different heights can be obtained. This may allow any nonlinearity or scaling errors in the profile determination system 127 to be compensated for, and the accuracy with which the electrical contacts 3 located at different heights are made to contact can be improved.

[0162] To accurately determine the position of the profile of the electrical contacts 3 on the DUT1 relative to the device table 103, it may be desirable to provide at least three reference structures 147 on the device table 103. In some embodiments, three or more reference structures 147 may be provided. For example, in the embodiment of Figure 10, eight reference structures 147 are provided.

[0163] Figure 11 shows a more detailed example of the standard structure 147. Figure 11A is a schematic side view of the standard structure 147. Figure 11B is a schematic perspective view of the standard structure 147. Figure 11C is a more detailed schematic view of the end of the standard structure 147.

[0164] The reference structure 147 comprises a columnar structure. The column may have a diameter of, for example, about 2-3 mm. The reference structure 147 includes a substantially spherical tip portion 149. The spherical tip portion 149 is surrounded by a substantially flat rim 151. The spherical tip portion 149 and the substantially flat rim 151 provide features that are easily identifiable in the determined profile of the device table 103. For example, the spherical tip portion 149 and the substantially flat rim 151 may make it relatively easy to fit geometric functions to the profile data. Thus, the position of the reference structure 147 relative to other features in the determined profile (e.g., electrical contacts 3 on the DUT1) can be easily identified.

[0165] The reference structure 147 may include other features that improve its visibility to the profile determination system 127. For example, a profile determination system 127 that measures radiation scattered from an object at an oblique angle (e.g., the profile determination system 127 shown in Figure 9) works particularly well when profiling an object that diffusely scatters a relatively large amount of radiation from the surface to be profiled. The reference structure 147 may be provided with roughness features on small scales that help increase the diffuse scattering of radiation from the reference structure 147. For example, the reference structure 147 may be provided with roughness features on a scale of about 50 microns or less. This can improve the visibility of the reference structure 147 to the profile determination system 127.

[0166] In some embodiments, the reference structure 147 may be provided with raised areas on its surface. These raised areas may be spaced, for example, about 40 microns apart. The raised areas can be considered an example of a roughness feature.

[0167] The reference structure 147 shown in Figure 11 includes a reference feature 153. The reference feature 153 indicates a reference point to which the probe end can be brought into contact with the reference structure 147. The reference feature may have dimensions approximately equal to the size of the probe ends 13, 15. Any reference made herein to a reference feature 153 having dimensions approximately equal to the size of the probe ends 13, 15 should be interpreted as meaning that the reference feature 153 has dimensions on the order of (or comparable to) the size of the probe ends 13, 15. It should be understood that a reference feature 153 having dimensions approximately equal to the size of the probe ends 13, 15 should not be limited to features having exactly the same size. As will be described in more detail below, the reference feature 153 is intended as a point to which the probe end can be guided in order to calibrate the position of the probe 7 relative to the device table 103. The extent to which the reference feature 153 and the probe ends 13, 15 are the same size can be determined by the required accuracy of the calibration.

[0168] In the embodiment shown in Figure 11, the reference feature 153 comprises a groove in the reference structure. The groove is substantially circular and extends around the vertex of the reference structure 147. The groove 153 may have a diameter of, for example, about 150 microns. The depth of the groove may be about 10 microns. In some embodiments, the reference feature 153 may include a plurality of circular grooves of different sizes extending around the vertex of the reference structure 147. In other embodiments, the reference feature 153 may comprise a laser-etched mark on the reference structure 147, a crosshair indicated on the reference structure 147 (for example, a pair of grooves forming a crosshair), or any other feature. In general, the reference feature 153 may include any feature that can be resolved by inspection (direct visual inspection or inspection by an inspection device (e.g., a camera or microscope)). This may allow a probe end to be guided to contact a reference point indicated by the reference feature 153.

[0169] As suggested above, the reference feature section 153 can be used to calibrate the position of the probe 7 relative to the device table 103. As described above, the position of the electrical contacts 3 on the DUT1 held by the device table 103 is determined by the profile determination system 127 relative to the reference structure 147 on the device table 103. It is desirable to accurately calibrate the moving mechanism 122 that determines the position of the probe 7 relative to the device table 103 in order to determine the configuration of the moving mechanism 122 that brings the probe ends 13, 15 into contact with the electrical contacts of the DUT1.

[0170] The moving mechanism 122 can be calibrated by bringing the probe 7 into contact with the reference structure 147. Since the position of the reference structure 147 on the device table 103 is known, bringing the probe 7 into contact with the reference structure 147 provides a known position for the probe 7 that can be used to calibrate the moving mechanism 122. To improve the accuracy of the calibration, the probe ends 13, 15 can be brought into contact with the reference structure 147 at or near a reference point indicated by a reference feature 153 on the reference structure 147. As described above, the reference feature 153 may have a size comparable to the size of the probe ends 13, 15. Thus, the reference feature 153 provides a more accurate reference point from which the probe ends can be precisely moved. For example, as shown in Figure 11C, the probe ends 13, 15 can be moved to be in contact with the reference structure in a circular groove 153.

[0171] The reference feature section 153 can, for example, surround the vertices of the reference structure 147. For example, in embodiments in which the reference feature section 153 includes a circular groove within the reference structure, the circular groove can extend around the vertices of the reference structure 147 (as shown in Figure 11C). The reference feature section 153 is substantially located at the vertices of the reference structure 147 and indicates a reference point within the range of the circular groove. The probe end can be brought into contact with the vertices of the reference structure (i.e., the reference point).

[0172] The reference feature portion 153 may be provided on a convex or protruding surface of the reference structure 147. This can reduce the possibility that the probe end may unintentionally come into contact with other areas of the reference structure 147.

[0173] In some embodiments, the moving mechanism 122 may be manually operated to bring the probe ends 13, 15 into contact with the reference structure. That is, the configuration of the moving mechanism 122 may be adjusted by a person until the probe ends 13, 15 are in contact with the reference structure 147. The test system 101 may include a calibration system that enables determination of the position of the probe ends 13, 15 relative to the reference structure 147. The calibration system may include, for example, a camera or microscope from which the probe ends 13, 15 and the reference structure 147 can be viewed. The moving mechanism 122 may be adjusted by an operator while viewing the probe ends 13, 15 and the reference structure 147 through the calibration system. The moving mechanism 122 may be adjusted until the probe ends 13, 15 are in contact with the reference structure 147 (for example, at or near a reference point indicated by the reference feature section 153).

[0174] This provides a reference for a known configuration of the moving mechanism 122, resulting in a known position of the probe 7 relative to the device table 103. This allows for other configurations of the moving mechanism 122, resulting in other positions of the probe 7 relative to the device table 103. Knowing the position of the electrical contacts 3 relative to the device table 103 allows the probe 7 to be precisely moved to contact the desired electrical contacts 3. In some embodiments, a reference feature 153 on a reference structure 147 may be detected by a profile determination system 127. Thus, the position of the reference feature 153 used during the calibration of the moving mechanism 122 may be detected in the profile of the electrical contacts 3 of the DUT 1. This can improve the accuracy of determining the position of the electrical contacts 3 relative to the position of the probe 7.

[0175] In some embodiments, to provide a further reference configuration of the moving mechanism 122 and to improve the accuracy of calibration, multiple probe ends 13, 15 of the probe 7 may be in contact with a reference structure 147 at different times. Calibration can be further improved by moving the probe 7 to contact multiple different reference structures 147 at different times. To accurately calibrate the moving mechanism in all directions, it is desirable that the probe 7 be in contact with reference structures 147 positioned at different locations in the x, y, and z directions.

[0176] The probe ends 13 and 15 can be brought into contact with the reference structure 147 in multiple different orientations. For example, the probe 7 can be rotated in different orientations (e.g., four or more different orientations) while in contact with the reference structure 147 (e.g., by changing the angle θ that the probe forms with the z-axis and / or by changing the angle φ that the probe forms with the x-axis). The different orientations of the probe 7 can provide further reference positions that can improve the calibration of the moving mechanism.

[0177] Embodiments of a calibration system configured to enable the determination of the position of the probe end relative to a reference structure 147, including a camera or microscope from which the probe end and the reference structure 147 can be viewed, have been described above. In some embodiments, the calibration system may include other components. For example, the calibration system may include a profile determination system 127, which can determine the profiles of the reference structure 147 and the probe end as the probe end is brought toward the reference structure 147. This may enable an operator to determine the position of the probe end relative to the reference structure 147 and to bring the probe end into contact with the reference structure 147.

[0178] In some embodiments, the calibration system may include means for detecting contact between the probe end and the reference structure. For example, the calibration system may include an electrical continuity tester for detecting electrical continuity between the probe end and the reference structure. The calibration system may include one or more pressure sensors on the probe and / or the reference structure, configured to detect contact between the probe end and the reference structure.

[0179] The calibration of the moving mechanism 122 can be updated without requiring the probe ends 13 and 15 to be in contact with the reference structure 147. For example, in some embodiments, the calibration of the moving mechanism 122 can be updated when the probe 7 is moved near the electrical contacts 3 of the DUT1 (e.g., during testing of the DUT1). The profile determination system 127 can determine the profiles of the probe ends 13 and 15 of the probe 7, and the profiles of the electrical contacts 3 in proximity to the probe ends 13 and 15. The determined profiles can be used to determine the position of the probe ends 13 and 15 relative to the electrical contacts 3. This can be used to determine the accuracy of the current calibration of the moving mechanism 122, and the calibration can be updated as needed. The calibration of the moving mechanism 122 can be updated, for example, after the probe 7 has been replaced with a new probe 7.

[0180] Figure 12 is a schematic diagram of an embodiment of the mount 104 shown in two perspective views. Figure 12 also shows a device table 103 that may be placed on the mount 104. The mount 104 is a kinematically restricted mount that restricts the movement of the device table 103 in multiple degrees of freedom. For example, a kinematically restricted mount 104 may restrict the movement of the device table 103 in all six degrees of freedom. Restricting the movement of the device table 103 may allow the device table 103 to be moved in a repeatable and controlled manner that enables precise positioning of the device table 103. In some embodiments, the device table 103 may be held in a fixed position on the mount 104, while the probe 7 may be moved around the device table 103 to contact different elements on the device table 103.

[0181] Mount 104 includes ball supports 157 that fit into mounting points 145 located on the underside of the device table 103. Mounting points 145 have a (sit) V-shaped groove in which the ball supports 157 are positioned. The ball supports 157 can slide along the groove-shaped mounting points 145 to adjust the orientation of the device table 103 relative to the mount 104. Each ball support 157 has two contact points with the (sit) groove-shaped mounting points 145 in which the ball support 157 is positioned. With three mounting points 145 and three ball supports 157, there are a total of six contact points. Each surface contact point may have its own normal direction. The combination of the six contact points serves to restrict the movement of the device table 103 in six degrees of freedom.

[0182] The mount 104 further comprises a vacuum seal 159. The vacuum seal 159 may allow the device table 103 to be vacuum-clamped to the mount 104. In other embodiments, the device table 103 may be clamped to the mount 104 using a different clamping mechanism. For example, the device table 103 may be clamped to the mount 104 magnetically, electrostatically, or mechanically. The vacuum seal may allow a vacuum pump to be fluidly connected to a vacuum port 139 on the device table 103 through the mount 104.

[0183] The mount 104 further comprises a cleaning pad 161. The cleaning pad 161 provides a surface on which the probe ends 13, 15 of the probe 7 can be cleaned. For example, the moving mechanism 122 can drag the probe ends 13, 15 over the cleaning pad 161, which can work to remove dirt, solder oxides, or other deposits from the probe ends 13, 15.

[0184] An embodiment of a test system 101 configured to determine the profile of electrical contacts 3 on one or more devices 1 before bringing the electrical contacts 3 into contact with probes 7 has been described above. Device profiling and probing may be performed in succession. For example, a device table 103 holding one or more devices 1 may be first profiled using a profile determination system 127. Subsequently, the device table 103 may move to a probing phase, in which one or more probes 7 are brought into contact with electrical contacts 3 on a DUT 1 located on the device table 103. The DUT 1 can then be tested using one or more probes 7. The profile of the device table 103 obtained during the profiling phase is used to determine the configuration of the moving mechanism 122 to be used during the probing phase to make contact with the electrical contacts 3 on the devices 1 on the device table 103.

[0185] To improve the throughput of the test system 101, the first device table 103 may be profiled while device 1 on the second device table 103 is probed. Once the first device table 103 has been profiled, it may be moved to the probing phase so that device 1 on the first device table 103 is probed. While device 1 on the first device table 103 is being probed, the third device table 103 may be profiled in preparation for probing device 1 on the third device table 103.

[0186] The test system 101 in Figure 6 includes a moving stage 106. The moving stage may be, for example, a linear moving stage 106 that can move the device table 103 between the profiling stage and the probing stage.

[0187] After the device table 103 has been profiled by the profile determination system 127, the configuration of the moving mechanism 122 to be used during the probing phase is determined (for example, by a controller). During the probing phase, the moving mechanism 122 may move one or both of the device table 103 and the probe 7 to several different positions and / or orientations so that the probe ends 13, 15 of the probe 7 are in contact with several different electrical contacts 3 on the DUT 1 located on the device table 103.

[0188] Prior to the probing phase, a set of configurations of the moving mechanism attempting to contact each of the electrical contacts to be tested in the shortest possible time can be determined. For example, a comprehensive search of possible moving mechanism sequences may be performed to find the sequence that minimizes the time required to perform the probing phase. Algorithms such as genetic algorithms or simulated annealing algorithms may be used to search for the optimal sequence of moving mechanism configurations.

[0189] Some forms of movement of probe 7 and / or device table 103 may be faster than other forms of movement. For example, rotation of probe 7 may take longer to perform than translation of probe 7. Therefore, a solution with fewer rotations of probe 7 during the probing phase may be sought. For example, a solution with a relatively small total number of different angular directions of probe 7 during the probing phase may be explored.

[0190] There may be several orientations of the probe 7 relative to the device table 103 that result in undesirable contact with the electrical contacts. For example, some configurations of the probe 7 may cause the probe ends 13 and 15 to slip on the electrical contacts 3. Slipping of the probe 7 may cause one of the probe ends 13 and 15 to move away from the electrical contacts 3. It may be desirable to seek a probe orientation in which the probe ends 13 and 15 are positioned relatively close to the highest point on the electrical contacts 3, thereby reducing the likelihood of the probe ends 13 and 15 slipping on the electrical contacts 3.

[0191] In some embodiments, the test system 101 may include multiple probes 7 (as shown in Figure 6). Multiple probes may be used to simultaneously test different DUT1 located on a single device table 103. In addition to this, or instead, multiple probes may be used to simultaneously test a single DUT1 through different electrical contacts 3. This can reduce the amount of time required to test a single DUT1 and / or the amount of time required to test all DUT1 located on the device table 103. Thus, the throughput of the test system 101 may be improved.

[0192] Various improvements to the test system enabling automated testing of multiple devices 1 have been described above. Ingenious improvements to the sampling module 18, radiation source, and delay line (e.g., as shown in Figure 4) are also intended herein and will be described below with reference to Figures 13-15.

[0193] Figure 13 is a schematic diagram of a portion of a test system 201 according to one embodiment of the present invention. The test system 201 shown in Figure 13 may be similar to the test system described above with reference to Figure 4, and may include many of the same or similar components.

[0194] The test system 201 includes a sampling module 203. The sampling module 203 includes first and second photoconductive elements 204, a signal generator (not shown in Figure 13), and a signal sampler (not shown in Figure 13). The sampling module 203 is similar to the sampling module 18 described above with reference to Figure 4, and will not be described in further detail here.

[0195] The sampling module is connected to the probe 207 via a coaxial cable 205. The probe 207 is in contact with the electrical contact 3 on the DUT1. The signal from the sampling module 203 is input to the DUT1 through the probe 207, and the signal reflection from the DUT1 is returned to the sampling module for analysis.

[0196] The test system 201 further comprises a radiation source 209, a beam splitter 211, and a delay line 213. The radiation source 209 may comprise a laser capable of emitting near-infrared radiation (for example, having wavelengths of approximately 800 nm, approximately 1000 nm, or approximately 1560 nm). The radiation beam 210 emitted from the radiation source 209 is incident on the beam splitter 211. The radiation beam 210 may be a pulsed radiation beam. The pulses of the radiation beam may have a pulse width of, for example, less than approximately 1 picosecond. The beam splitter 211 splits the radiation beam 210 into a generating beam 215 and a receiving beam 217. The generating beam 215 and the receiving beam 217 are coupled to an optical fiber 207 and transmitted to a sampling module 203. In the sampling module 203, the generating beam is directed to incident on a first photoconductive element 204, and the receiving beam is directed to incident on a second photoconductive element 204.

[0197] The delay line 213 is positioned in the optical path of the received beam 217 and is configured to introduce an optical delay between the pulses of the generated beam 215 and the pulses of the received beam 217. The delay line 213 may be similar to the delay line 37 described above with reference to Figure 4 and may include one or more reflectors attached to a moving stage (not shown in Figure 13). The moving stage may be moved to scan the optical delay between the generated beam 215 and the received beam 217.

[0198] Conventional delay line configurations include separate slow-scan delay lines and fast-scan delay lines. The fast-scan delay line may be a galvanometer-driven delay line. In such configurations, the fast-scan delay line may not provide a sufficiently large delay time range. For example, the fast-scan delay line may introduce a maximum optical delay of about 50 picoseconds. In a conventional configuration, data segments may be acquired over a delay time range of 50 picoseconds (corresponding to the maximum optical delay of the fast-scan delay line), in which case the slow-scan delay line may be moved to acquire another data segment over another 50-picosecond range of delay time. The different data segments are then concatenated to obtain a complete dataset. The process of acquiring multiple different datasets at different locations on the slow-scan delay line can result in a large acquisition time to obtain a complete dataset.

[0199] In the embodiment shown in Figure 13, only a single delay line 213 is used. The delay line 213 can scan over a wide range of delay times at speeds comparable to those obtained using a galvanometer-driven delay line. The delay line 213 is a direct-driven delay line that includes a synchronous linear motor configured to move a reflector to vary the optical delay introduced by the delay line 213. The linear motor may be brushless, which reduces friction in the motor and improves efficiency. The moving stage may be equipped with high-quality crossed-roller bearings or air bearings. In contrast, prior art delay line configurations use a ball-screw drive to limit the maximum speed and acceleration of the moving stage. The ball-screw also introduces several levels of backlash, which are avoided by the direct-driven delay line intended herein.

[0200] Compared to the configuration of the prior art, the overall acquisition time of measurements obtained using the direct drive line discussed herein can be significantly improved. For example, the acquisition time may be about 60 times faster than that achievable with the prior art configuration.

[0201] The test system 201 in Figure 13 further comprises a digital sampling module 219. The digital sampling module 219 receives a first signal 221 from a delay line 213 and a second signal 223 from a sampling module 203. The digital sampling module 219 simultaneously samples the first and second signals 221 and 223, maintaining matching between the two signals so that the data from the sampling module can be assigned to a specific delay time introduced by the delay line 213. The digital sampling module interfaces with a controller 225, which may be a computer. The controller 225 can store the data sampled by the digital sampling module 219.

[0202] Figure 14 is a schematic diagram of a delay line configuration forming part of a test system according to one embodiment of the present invention. The configuration shown in Figure 14 includes a radiation source 301 that emits a radiation beam 303. The radiation beam 303 is incident on a beam splitter 305, which splits the radiation beam into a generated beam 307 and a received beam 309. Both the generated beam 307 and the received beam 309 are supplied to the delay line configuration. The delay line configuration includes a first reflector unit 311 that receives the generated beam 307 and a second reflector unit 313 that receives the received beam 309. The first and second reflector units 311 and 313 may each include a single reflector or multiple reflectors. The first and second reflector units 311 and 313 may include corner cube reflectors.

[0203] The first and second reflector units 311 and 313 are mounted on a movable stage 315. The movable stage 315 is movable in a first direction 317 and a second direction 319. Movement of the movable stage 315 in the first direction 317 increases the optical path length of the generated beam 307 and decreases the optical path length of the received beam 309. Movement of the movable stage 315 in the second direction 319 decreases the optical path length of the generated beam 307 and increases the optical path length of the received beam 309.

[0204] In the configuration shown in Figure 14, the movement of the movable stage 315 changes the optical path lengths of the generated beam and the received beam in opposite directions. As a result, a movement of the movable stage 315 by a first distance introduces a difference in the optical path lengths of the generated beam and the received beam that is at least twice the first distance. Therefore, a smaller movement of the movable stage is required to change the optical delay between the generated beam and the received beam by a given amount (compared to the prior art configuration). This advantageously enables faster scanning of the optical delay. Consequently, the acquisition time required to perform a given measurement can be significantly reduced.

[0205] In the embodiment shown in Figure 14, the delay line configuration further comprises a prism 321 (e.g., a roof prism) located in the optical paths of the generated beam 307 and the received beam 309. The prism can reflect radiation to the first and second reflector units 311 and 313 such that the radiation pulses undergo multiple reflections in the reflector units 311 and 313. By causing the radiation pulses to undergo multiple reflections in the reflector units 311 and 313, the total optical path of the pulses through the delay line configuration is increased. This can increase the optical delay introduced between the pulses of the generated beam and the received beam.

[0206] The generated beam 307 and the received beam 309 output from the delay line configuration are coupled to an optical fiber 321 by a coupler 323. The optical fiber 321 can transmit the generated beam and the received beam to the sampling module.

[0207] Figure 15 is a schematic diagram of a radiation feedback system that may form part of a test system according to one embodiment of the present invention. The configuration shown in Figure 15 comprises a radiation source 401 (e.g., a laser) that emits a radiation beam 403. The radiation beam 403 is coupled to an optical fiber 405. The optical fiber 405 may be used to transmit the radiation beam 403 to a sampling module (as described above with reference to other embodiments). The fiber coupling efficiency of the optical fiber 405 may change over time. For example, the coupling efficiency may change over time due to changes in the temperature of the fiber 405 or other factors such as creep of the optical components used to couple the radiation beam 403 to the fiber 405.

[0208] Changes in the fiber coupling efficiency of optical fiber 405 will result in changes in the output of the radiation beam output from optical fiber 405 (and which may also be supplied to the sampling module). It may be desirable to maintain a substantially constant average output of the radiation output from optical fiber 405 and supplied to the sampling module.

[0209] A radiation feedback system is provided to stabilize the output of the radiation emitted from the optical fiber 405. The radiation feedback system comprises a radiation sensor 409, an attenuator 413, and a controller 411. The radiation beam 403 emitted from the optical fiber 405 is incident on a beam splitter 407. The beam splitter 407 directs a first portion 408 of the radiation beam to the radiation sensor 409. A second portion 410 of the radiation beam can be supplied, for example, to a sampling module.

[0210] The radiation sensor 409 is configured to detect the intensity of radiation emitted from the optical fiber 405 (the radiation may include radiation pulses). The attenuator 413 is positioned in the optical path of the radiation beam emitted from the radiation source 401, before the radiation beam is coupled to the fiber 405. The attenuator 413 is configured to reduce the intensity of the radiation beam by an adjustable amount. The controller 411 is configured to adjust the amount by which the attenuator reduces the intensity of the radiation beam in response to the radiation sensor 409's measurement of the radiation beam intensity. For example, if the radiation sensor 409 detects an increase in the intensity of the radiation beam 403, the controller 411 can act to increase the amount by which the attenuator 413 attenuates the radiation beam 403. If the radiation sensor 409 detects a decrease in the intensity of the radiation beam 403, the controller 411 can act to decrease the amount by which the attenuator 413 attenuates the radiation beam 403. Thus, the radiation feedback system can act to maintain a substantially constant average output of the radiation beam emitted from the optical fiber 405.

[0211] The radiation beam may be pulsed, and the radiation feedback system may act to maintain a substantially constant average output of the radiation beam, where the average is obtained for more than one pulse period. The radiation feedback system may not act to alter the time profile of individual pulses. In some embodiments, the pulse repetition rate of the radiation beam can be about 100 MHz (i.e., a pulse period of 10 nanoseconds). The radiation feedback system may act to reduce output instability at frequencies below about 1 kHz.

[0212] The controller 411 may comprise a proportional-integral-derivative (PID) controller. The attenuator 413 may include a liquid crystal variable retarder that, in combination with a polarizing element, can provide voltage-controlled attenuation of the radiation beam 403. In other embodiments, different types of attenuators may be used. For example, the attenuator 413 may comprise a motorized variable neutral-density filter wheel, an acousto-optic modulator, or an electro-optic modulator.

[0213] In some embodiments, one or more optical components of the test system may be fiber-based. For example, any of the radiation sources described herein may include a fiber laser. In addition to, or instead of, the beam splitters or radiation sources described herein may be optical fiber based. In some embodiments, one or more components of a delay line may be optical fiber based. A fiber-based delay line may include a portion of an extended optical fiber (e.g., using a piezoelectric bobbin). However, a fiber-based delay line may not achieve the range of delay times possible with a free-space delay line as described herein. Therefore, a test system including a delay line may not have all of the optical components based on optical fiber.

[0214] In embodiments including a dual-laser system in which the optical delay between the generating beam and the receiving beam can be adjusted by coordinating the synchronization between the two lasers, the entire path of the generating beam and / or the receiving beam can be based within an optical fiber.

[0215] Various ingenious embodiments of the test system have been described above and are shown in the drawings in relation to specific embodiments of the present invention. It will be recognized that any of the described and / or illustrated embodiments can be combined in a single embodiment. For example, one or more features of one embodiment can be combined with one or more features of another embodiment. Although several embodiments containing one or more ingenious embodiments have been described, it will be further recognized that embodiments containing only a single ingenious embodiment are also intended herein. In general, any feature of any of the described embodiments may be used alone or in any combination with any of the other features of the described embodiment.

[0216] While specific embodiments of the present invention have been described above, it will be understood that the present invention can be carried out in ways other than those described. The above description is illustrative and not limiting. Accordingly, it will be apparent to those skilled in the art that modifications can be made to the described invention without departing from the scope of the claims set forth below. [Example 1] A test system for testing a device having multiple electrical contacts, wherein the test system is A device table capable of holding at least one device under test, A probe including at least one probe end for contacting the electrical contacts of the device under test, A movable mechanism that can move one or both of the device table and the probe, and move the at least one probe end to contact at least one electrical contact of the device under test, A test system comprising a profile determination system configured to determine the profile of the electrical contacts of a device under test. [Example 2] The profile determination system, A radiation source configured to irradiate at least a portion of the device under test, A radiation sensor configured to detect radiation scattered from the electrical contacts of the device under test, The test system according to Example 1, further comprising a controller configured to determine the profile of the electrical contacts of the device under test from the detected scattered radiation. [Example 3] The test system according to Example 2, wherein the radiation sensor is positioned such that different parts of the device under test, which extend by different amounts away from the device table, appear at different positions within the field of view of the radiation sensor. [Example 4] The test system according to Example 3, wherein the radiation sensor is oriented at an oblique angle with respect to the propagation direction of the radiation emitted from the radiation source. [Example 5] The test system according to any one of Examples 2 to 4, wherein the radiation source is configured to irradiate the strip of the device under test with a radiation strip. [Example 6] The test system according to Example 5, wherein the radiation sensor is configured to detect radiation scattered from an electrical contact located within the radiation strip, and the controller is configured to determine the height of a point on the device under test located within the irradiated strip. [Example 7] The test system according to Example 6, wherein the moving mechanism is operable to move one or both of the device table and the radiation source to scan the radiation strip on the device under test, and the controller is configured to determine the profile of the electrical contacts of the device under test by combining the heights of determined points on the device under test at different locations on the radiation strip. [Example 8] The test system according to any one of Examples 1 to 7, wherein the device table includes a plurality of reference structures extending outside or into the device table, and the profile determination system is configured to determine the position of the profile of the electrical contacts of the device under test relative to the positions of the reference structures. [Example 9] The test system according to Example 8, wherein the reference structure extends outside the device table, and at least two of the reference structures extend outside the device table by different distances. [Example 10] The test system according to Example 8 or Example 9, wherein the moving mechanism is operable to move one or both of the device table and the probe so that at least one of the probe ends contacts one of the reference structures. [Example 11] The test system according to Example 10, further comprising a calibration system configured to enable determination of the position of the at least one probe end relative to the reference structure. [Example 12] The test system according to any one of Examples 1 to 11, wherein the profile determination system is further configured to determine the position of the probe end relative to the electrical contacts of the device under test. [Example 13] A test system according to any one of Examples 1 to 12, further comprising a controller configured to determine the configuration of the moving mechanism that brings the at least one probe end into contact with at least one electrical contact of the device under test, based on the determined profile of the electrical contacts of the device under test. [Example 14] A test system for testing a device having multiple electrical contacts, wherein the test system is A device table capable of holding at least one device under test, A probe including at least one probe end for contacting the electrical contacts of the device under test, The device table and the probe, or both thereof, are moved by a movable mechanism that is operable to bring at least one probe end into contact with at least one electrical contact of the device under test. A test system comprising a device table including a plurality of reference structures extending outside or into the device table. [Example 15] The test system according to Example 14, wherein at least two of the reference structures extend outside or inside the device table by different distances. [Example 16] The test system according to Example 14 or Example 15, wherein the moving mechanism is operable to move one or both of the device table and the probe so that at least one of the probe ends contacts one of the reference structures. [Example 17] The test system according to Example 16, further comprising a calibration system configured to enable determination of the position of the at least one probe end relative to the reference structure. [Example 18] The test system according to Example 16 or Example 17, wherein at least one of the reference structures includes a reference feature portion indicating a reference point on the reference structure, and the moving mechanism is operable to move one or both of the device table and the probe so that at least one of the probe ends contacts the reference point. [Example 19] The test system according to Example 18, wherein the reference feature includes a substantially circular groove formed within the reference structure, extending around the apex of the reference structure. [Example 20] The test system according to Example 19, wherein the reference structure includes a plurality of substantially circular grooves formed within the reference structure, each groove extending around the apex of the reference structure. [Example 21] The test system according to any one of Examples 14 to 20, wherein at least one of the reference structures comprises a substantially spherical tip portion. [Example 22] The test system according to Example 21, wherein the spherical tip portion is surrounded by a substantially flat rim. [Example 23] The test system according to any one of Examples 14 to 22, wherein at least one of the reference structures has a surface having a scale roughness characteristic of 50 microns or less. [Example 24] The test system according to any one of Examples 1 to 23, wherein the device table is operable to hold multiple devices under test. [Example 25] The test system according to any one of Examples 1 to 24, further comprising a kinematically restricted mount to which the device table is attached, wherein the kinematically restricted mount is configured to restrict the movement of the device table in multiple degrees of freedom. [Example 26] A test system according to any one of Examples 1 to 25, further comprising a loading device capable of automatically loading the device under test and unloading it from the device table. [Example 27] A signal generator configured to generate a signal, guide the signal through at least one of the probe ends, and, when in use, guide the signal to the device under test through the electrical contacts of the device under test, A test system according to any one of Examples 1 to 26, further comprising a signal sampler configured to sample a signal passing through at least one of the probe ends, wherein during use, a signal reflected by the device under test and passing through the probe ends is sampled by the signal sampler. [Example 28] The test system according to Example 27, wherein the signal generator is configured to generate a broadband signal having frequency components in the range of 0.01 GHz to 10 THz. [Example 29] The signal generator, A pulsed radiation source, A first signal conversion device is arranged to receive radiation pulses from the pulsed radiation source and configured to output signal pulses in response to irradiation from the pulsed radiation source. The test system according to Example 27 or Example 28, further comprising a transmission line configuration configured to guide the signal pulse from the first signal conversion device through at least one of the probe ends. [Example 30] The signal sampler, A second signal conversion device arranged to receive radiation pulses from the pulsed radiation source, comprising a second signal conversion device that samples the signal pulses received by the second signal conversion device in response to irradiation from the pulsed radiation source, The test system according to Example 29, wherein the transmission line configuration is configured to guide signal pulses reflected from or transmitted through the device under test and passing through at least one of the probe ends to the second signal conversion device. [Example 31] A test system for testing a device, wherein the test system is A pulsed radiation source configured to supply a generated radiation beam and a received radiation beam, wherein the generated radiation beam and the received radiation beam are pulsed radiation beams, A first signal conversion device is positioned to receive pulses of the generated radiation beam and configured to output signal pulses in response to receiving pulses of the generated radiation beam. A second signal conversion device is positioned to receive pulses of the received radiation beam and configured to sample signal pulses in response to receiving pulses of the received radiation beam. A transmission line configuration configured to guide signal pulses from the first signal conversion device to the device under test, and to guide signal pulses reflected from the device under test through the device under test to the second signal conversion device, A direct-drive delay line positioned within the optical paths of the generated radiation beam and / or the received radiation beam, the delay line is configured to introduce an optical delay between the generated radiation beam and the received radiation beam, wherein the pulses of the generated radiation beam are incident on the first signal conversion device at a different time than the corresponding pulses of the received radiation beam incident on the second signal conversion device. The aforementioned delay line, At least one reflector positioned within the optical path of the generated radiation beam and / or the received radiation beam, A test system comprising a synchronous linear motor configured to move the reflector and change the optical path length of the generated radiation beam and / or the received radiation beam, thereby changing the optical delay between the generated radiation beam and the received radiation beam. [Example 32] A test system for testing a device, wherein the test system is A pulsed radiation source configured to supply a generated radiation beam and a received radiation beam, wherein the generated radiation beam and the received radiation beam are pulsed radiation beams, A first signal conversion device is positioned to receive pulses of the generated radiation beam and configured to output signal pulses in response to receiving pulses of the generated radiation beam. A second signal conversion device is positioned to receive pulses of the received radiation beam and configured to sample signal pulses in response to receiving pulses of the received radiation beam. A transmission line configuration configured to guide signal pulses from the first signal conversion device to the device under test, and to guide signal pulses reflected from the device under test through the device under test to the second signal conversion device, A first reflector positioned in the optical path of the generated radiation beam, A second reflector positioned within the optical path of the received radiation beam, and A test system comprising a delay line including a movable stage to which the first reflector and the second reflector are attached, wherein movement of the movable stage in a first direction increases the optical path length of the generated radiation beam and decreases the optical path length of the received radiation beam, and movement of the movable stage in a second direction decreases the optical path length of the generated radiation beam and increases the optical path length of the received radiation beam. [Example 33] A test system for testing a device, wherein the test system is A pulsed radiation source configured to supply a generated radiation beam and a received radiation beam, wherein the generated radiation beam and the received radiation beam are pulsed radiation beams, A first signal conversion device is positioned to receive pulses of the generated radiation beam and configured to output signal pulses in response to receiving pulses of the generated radiation beam. A second signal conversion device is positioned to receive pulses of the received radiation beam and configured to sample signal pulses in response to receiving pulses of the received radiation beam. A transmission line configuration configured to guide signal pulses from the first signal conversion device to the device under test, and to guide signal pulses reflected from the device under test through the device under test to the second signal conversion device, A radiation sensor configured to detect the intensity of radiation pulses emitted from the pulsed radiation source, An attenuator is placed in the optical path of the radiation pulse emitted from the pulsed radiation source and configured to reduce the intensity of the radiation pulse by an adjustable amount, and A test system comprising a radiation feedback system including a controller configured to adjust the amount by which the attenuator reduces the intensity of the radiation pulse in response to a measurement of the intensity of the radiation pulse by the radiation sensor.

Claims

1. A test system for testing a device having multiple electrical contacts, wherein the test system is A device table capable of holding at least one device under test, A probe including at least one probe end for contacting the electrical contacts of the device under test, A movable mechanism that can move one or both of the device table and the probe, and move the at least one probe end to contact at least one electrical contact of the device under test, It has, The device table includes a plurality of reference structures extending outside or within the device table. Testing system.

2. The test system according to claim 1, wherein at least two of the reference structures extend outside or inside the device table by different distances.

3. The test system according to claim 1 or 2, wherein the moving mechanism is operable to move one or both of the device table and the probe such that at least one of the probe ends contacts one of the reference structures.

4. The test system according to claim 3, further comprising a calibration system configured to enable the determination of the position of the at least one probe end relative to the reference structure.

5. The test system according to claim 3 or 4, wherein at least one of the reference structures includes a reference feature portion indicating a reference point on the reference structure, and the moving mechanism is operable to move one or both of the device table and the probe such that at least one of the probe ends contacts the reference point.

6. The test system according to claim 5, wherein the reference feature portion has a substantially circular groove formed within the reference structure and extending around the apex of the reference structure.

7. The test system according to claim 6, wherein the reference feature portion has a plurality of substantially circular grooves formed within the reference structure, each groove extending around the apex of the reference structure.

8. The test system according to any one of claims 1 to 7, wherein at least one of the reference structures has a substantially spherical tip portion.

9. The test system according to claim 8, wherein the spherical tip portion is surrounded by a substantially flat rim.

10. The test system according to any one of claims 1 to 9, wherein at least one of the reference structures has a surface having a scale roughness characteristic of 50 microns or less.

11. The test system according to any one of claims 1 to 10, wherein the device table is operable to hold a plurality of devices under test.

12. The test system according to any one of claims 1 to 11, further comprising a kinematically restricted mount to which the device table is attached, wherein the kinematically restricted mount is configured to restrict the movement of the device table in a plurality of degrees of freedom.

13. The test system according to any one of claims 1 to 12, further comprising a loading device capable of automatically loading a device under test and unloading it from the device table.

14. A signal generator configured to generate a signal, guide the signal through at least one of the probe ends, and, when in use, guide the signal to the device under test through the electrical contacts of the device under test, A signal sampler configured to sample a signal passing through at least one of the probe ends, wherein during use, the signal reflected by the device under test and passing through the probe ends is sampled by the signal sampler. A test system according to any one of claims 1 to 13, further comprising:

15. The test system according to claim 14, wherein the signal generator is configured to generate a broadband signal having frequency components in the range of 0.01 GHz to 10 THz.

16. The aforementioned signal generator is A pulsed radiation source, A first signal conversion device is arranged to receive radiation pulses from the pulsed radiation source and is configured to output signal pulses in response to irradiation from the pulsed radiation source. A transmission line configuration configured to guide the signal pulse from the first signal conversion device through at least one of the probe ends, The test system according to claim 14 or claim 15, comprising:

17. The aforementioned signal sampler is A second signal conversion device arranged to receive radiation pulses from the pulsed radiation source, the second signal conversion device samples the signal pulses received by the second signal conversion device in response to irradiation from the pulsed radiation source. It has, The test system according to claim 16, wherein the transmission line configuration is configured to guide signal pulses reflected from or transmitted through the device under test and passing through at least one of the probe ends to the second signal conversion device.

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