Probe head for testing an electronic device comprising an integrated optical element

Abstract

A probe head (10) for an electronic device testing apparatus comprises: a plurality of contact probes (11) configured to electrically and mechanically contact contact pads (12a) of a device under test (13); at least one guide (20) having a plurality of guide holes (20h) for slidably accommodating the plurality of contact probes (11); a storage element (40) configured to support the guide (20) and accommodate at least one portion of the plurality of contact probes (11), the storage element (40) having a first portion (40a) and a second portion (40b) movable relative to the first portion (40a); a moving means (60) configured to move the second portion (40b) of the storage element (40) relative to the first portion (40a); and at least one test optical signal distribution element (50) configured to transmit a test optical signal to the device under test (13). Preferably, the test optical signal distribution element (50) is associated with the second part (40b) of the storage element (40) and is configured to be moved integrally therewith by a moving means (60), said moving means (60) being configured to enable alignment of said test optical signal distribution element (50).

Description

Technical Field

[0001] The present invention relates to a probe head for testing an electronic device having integrated optical elements, such as, for example, an electronic device integrated in a semiconductor wafer and including a photonic integrated circuit, and the following disclosure is made with reference to the technical field of the present application only for the purpose of simplifying the description thereof.

Background Art

[0002] As is well known, a probe head is basically a device configured to electrically connect a plurality of contact pads of microstructures, particularly electronic devices integrated on a semiconductor wafer, to corresponding channels of a test apparatus for performing their functional checks, particularly electrical or general tests.

[0003] Tests performed on a plurality of integrated circuits particularly serve to detect and separate a plurality of defective circuits already in the manufacturing stage. Usually, the probe head is in that case used to electrically test a plurality of circuits integrated on a wafer before their dicing and mounting in a chip storage package.

[0004] The probe head is generally plate-shaped and usually includes a plurality of movable contact probes held by at least a pair of supports or guides parallel to each other. The plate-shaped supports provided with specific holes are usually arranged at a specific distance from each other to leave a free zone or an air zone for moving and, in some cases, deforming contact probes formed of wires of a special alloy having good electrical and mechanical properties.

[0005] A good connection between the contact probe and the contact pads of the device under test is ensured by the pressure of the probe head on the device, and the contact probe movable within a plurality of guide holes formed within a plurality of guides is subject to bending within the air zone and sliding within the plurality of guide holes during the pressing contact. This type of probe head is commonly referred to as a vertical probe head.

[0006] In some cases, a plurality of contact probes are fixedly attached to the head on a plate-like upper support: in this case, they are called a plurality of probe heads having a plurality of blocked probes. However, more often, a plurality of probe heads having probes that are not fixedly blocked but are interfaced, optionally by micro-contacts, to a so-called board are used: they are called a plurality of probe heads having a plurality of unblocked probes. Micro-contacts are commonly referred to as "space transformers". This is because, in addition to contacting a plurality of probes, it further enables spatially redistributing a plurality of contact pads formed thereon with respect to the contact pads on the device under test, particularly by relaxing the distance constraint between the centers of the plurality of pads.

[0007] In recent years, so-called photonic integrated circuits (PIC, abbreviated from "Photonic Integrated Circuits") that have low dissipated power compared to conventional electronic technologies while being able to achieve extremely high (on the order of THz) data transmission speeds have made significant progress. This technological progress has been promoted particularly by the need to integrate high-speed transmission paths between a plurality of electronic devices and between a plurality of elements within those devices.

[0008] In order to integrate optical transmission means within an electronic chip, the confinement and transmission of light are carried out by forming an integrated waveguide using silicon in combination with a substrate formed from a material such as an oxide or other dielectric having a lower refractive index. The waveguide on the silicon may have dimensions smaller than a micron and, thus, can be easily integrated within the chip, thereby enabling the integration of optical and electrical components within CMOS components and generating devices with higher speeds, much higher computing capabilities, and also higher performance from an energy perspective.

[0009] The problem with these devices is due to the coupling of light within the waveguide of the chip, which can also be observed during its test phase.

[0010] In particular, in order to test a device equipped with electronic components and simultaneously integrated optical components, it is necessary to obtain, on the one hand, the optical coupling between the optical signal coming from the test apparatus and the waveguide of the device under test, and on the other hand, the conventional electrical and mechanical contact by means of contact probes.

[0011] In fact, according to the known solutions, the contact probe contacts the contact pads of the device under test and supplies it via the power and ground probes in order to confirm the electrical operation of the device via the signal probe. Furthermore, in a system equipped with a photonic integrated circuit, the chip has an input / output optical interface and, in order to test the above components, it is necessary to couple light into the waveguide via the above optical interface and detect the emitted light, as schematically shown in FIG. 1. In particular, in FIG. 1, the probe head 1 can send an electronic signal 2a (via a conventional contact probe not shown) and an optical signal 2b (also via an optical element within a general waveguide not shown) to the device under test 3, which is equipped with a conventional contact pad 4a for electrical coupling and an optical interface 4b for optically coupling the optical signal coming from the probe head 1.

[0012] Generally, the test of the device under test begins with an optical alignment routine in which several circular motions (indicated in the technical field as "helical" motion) of the waveguides of the probe head are performed, while the quality of the optical coupling (in particular, the value of the coupled optical power in the device) is continuously checked. When the signal power reaches the target value, the test can begin. The accuracy required for this type of procedure is on the order of about ±100 nm.

[0013] According to some known solutions, a plurality of probe heads can be coupled to an external mechanical system, such as a movable mechanical arm, on which an array of waveguides (e.g., optical fibers) intended for the optical test of the device is mounted. These probe heads are usually equipped with a plurality of contact probes of the cantilever type. The plurality of probe heads then provide a free space for moving the arm carrying the waveguide, and thus the size has to be increased.

[0014] Generally, it is difficult to reliably ensure the alignment of the waveguides with the optical interface of the device under test in a simple way, which can be obtained with complex dynamics in known solutions.

[0015] The relative alignment between the optical components inside the probe head and the electrical contact probes, for example, the relative alignment in a plane parallel to the plane (e.g., the x-y plane of the reference system of the figure) in which the device under test is located, and the relative alignment requiring an accuracy of at least 100 nm is also ensured.

[0016] Finally, it is also important to ensure the accurate vertical positioning (i.e., along the z-axis of the reference system of the figure) of the optical elements of the probe head. SUMMARY OF THE INVENTION PROBLEMS TO BE SOLVED BY THE INVENTION

[0017] The technical problem of the present invention is to have functional and structural features that enable the elimination of the constraints and drawbacks still affecting the probe head made according to the prior art. In particular, without complicating the structure of the head, while maintaining high quality at the same time, to devise a probe head that enables simple and stable alignment of a plurality of optical components integrated therein. In particular, it is desirable to obtain a simple integration of the optical and electrical parts in order to avoid coupling the probe head to an external mechanical system and to enable electrical / optical testing of more devices in parallel.

Means for Solving the Problem

[0018] The idea of the solution underlying the present invention is to provide a probe head having a plurality of vertical probes, with a pair of guides between which a storage element (also called a housing) is arranged, the vertical probe head technology being combined with the presence, inside the probe head, of optical elements (in particular waveguides) for testing a plurality of devices including a photonic integrated device, especially in relation to the lower guide, the optical elements being integrated inside the probe head and forming a simple and compact structure. In particular, the storage element comprises a fixed part (for example, an external frame) and a movable part (for example, a central core) connected thereto via a ceramic support in which at least the waveguide for optical testing is specified, and simple moving means such as piezoelectric transducers are present to move the movable part to obtain a fine and accurate alignment of the optical elements with respect to the optical interface of the device under test. In this way, both the contact probes and the waveguides are associated with the same storage element of the probe head, and only the movement of the movable part of the storage element is necessary to obtain an optical alignment while obtaining a compact structure that enables the use of the vertical probes housed in the guides and within the storage element. The designed architecture further enables a simple relative alignment between the contact probes and the optical elements, similar to a simple adjustment of the distance in the vertical direction, by simply moving the ceramic support of the waveguide.

[0019] Therefore, it is possible to test optoelectronic devices via vertical probes without the assistance of complex and expensive precision mechanisms.

[0020] Based on the idea of such a solution, the above technical problem is solved by a probe head for testing an electronic device, which includes a plurality of contact probes configured to electrically and mechanically contact the contact pads of the device under test, at least one guide having a plurality of guide holes for slidably accommodating the plurality of contact probes, a storage element configured to support the guide and accommodate at least one portion of the plurality of contact probes, the storage element including a first portion and a second portion movable relative to the first portion, moving means configured to move the second portion of the storage element relative to the first portion, and at least one test optical signal distribution element configured to transmit a test optical signal to the device under test, the test optical signal distribution element being associated with the second portion of the storage element and configured to be integrally moved therewith by the moving means, and the moving means being configured to enable alignment of the test optical signal distribution element.

[0021] In particular, the present invention comprises the following further and optional features, which may be employed individually or in combination, if required.

[0022] According to one aspect of the present invention, the guide may be configured as a first guide portion connected to the first portion of the storage element and a second guide portion connected to the second portion of the storage element and configured to move with the second portion of the storage element.

[0023] According to one aspect of the present invention, the plurality of contact probes may be associated with the first portion of the storage element and configured to remain stationary during movement of the second portion of the storage element.

[0024] More particularly, the plurality of contact probes may be associated with the first portion of the storage element (in particular, may be received in a guide hole formed in the first guide portion), and the test optical signal distribution element may be associated with (connected to) the second portion of the storage element via the second guide portion.

[0025] According to another aspect of the present invention, the plurality of contact probes may further be associated with the second portion of the storage element and may be configured to move integrally with the second portion and the test optical signal distribution element.

[0026] More particularly, the second guide portion may include a first guide structure including a plurality of guide holes for accommodating the plurality of contact probes, and a second guide structure configured to accommodate the test optical signal distribution element, wherein the second guide structure may be structurally independent of the first guide structure.

[0027] The test optical signal distribution element may also be directly connected to the first portion of the storage element.

[0028] According to one aspect of the present invention, the moving means may be at least two piezoelectric transducers, each of the piezoelectric transducers being configured to cause a linear movement of the second portion of the storage element in a specific direction.

[0029] Furthermore, the plurality of contact probes may include a body extending in a vertical direction along a longitudinal axis between a first end and a second end. The first end may be configured to contact, for example, an interface board interfacially connected to the probe head, and the second end may be configured to contact the contact pad of the device under test.

[0030] According to another aspect of the present invention, the test optical signal distribution element may be connected to the guide of the probe head, for example, to the surface of the guide facing the device under test. In particular, it may be adhered to the surface of the guide.

[0031] According to another aspect of the present invention, the above-described guide may be a lower guide, and the probe head may further include an upper guide, and the storage element may be arranged between the lower guide and the upper guide.

[0032] According to another aspect of the present invention, the test optical signal distribution element may include a first alignment hole, the second guide portion of the lower guide may include a second alignment hole, and the upper guide may include a third alignment hole. The plurality of alignment holes are arranged and configured such that when the centers of the alignment holes of the test optical signal distribution element are aligned along respective predetermined axes with the center of the corresponding alignment hole of the second guide portion and the center of the corresponding alignment hole of the upper guide, it enables the passage of a plurality of alignment pins to ensure mutual alignment between the plurality of contact probes and the test optical signal distribution element connected to the second guide portion of the lower guide.

[0033] According to an aspect of the present invention, the plurality of alignment holes can be obtained by laser drilling with an accuracy of less than 3 μm.

[0034] Furthermore, the upper guide may be made of a single piece.

[0035] According to still another aspect of the present invention, the test optical signal distribution element may include a glass or plastic body and a plurality of waveguides formed within the glass or plastic body and configured to guide light from a light source toward the device under test.

[0036] According to still another aspect of the present invention, the test optical signal distribution element may be configured to couple light through a grating coupler of the optical interface of the device under test.

[0037] According to still another aspect of the present invention, the probe head of the present invention includes at least one spacer element disposed between the storage element and the guide (for example, between the storage element and the second guide structure), and the spacer element may be removable to enable adjustment of the distance between the test optical signal distribution element and the device under test.

[0038] Furthermore, the storage element may include at least one deformable arm connecting its first part and its second movable part to each other.

[0039] Finally, the first part of the storage element may be its peripheral part, and the second part of the storage element may be its central part.

Advantages of the Invention

[0040] The features and advantages of the probe head according to the present invention will result from the following description of its embodiments, which is given by way of non-limiting example with reference to the accompanying drawings.

Brief Description of the Drawings

[0041]

Figure 1

Figure 2A

Figure 2B

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8A

Figure 8B

Figure 9A

Figure 9B

Figure 9C

Figure 10A

Figure 10B

Figure 11A

Figure 11B

Figure 12

DETAILED DESCRIPTION OF THE INVENTION

[0042] Referring to the figures, a probe head made according to the present invention is shown generally and schematically at reference numeral 10.

[0043] The plurality of figures represent schematic diagrams and are not drawn to scale, but it should be noted that instead they are drawn to emphasize the important features of the present invention. Further, in the plurality of figures, different components are schematically drawn and their forms may vary according to the desired application field. Further, it should be noted that in the plurality of figures, the same reference numerals represent components that are the same in form or function. Finally, specific improvements described with respect to an embodiment shown in one figure may also be used in other embodiments shown in other figures.

[0044] As described below, in its more general form, the probe head 10 is an integrated electronic device on a semiconductor wafer, and the electronic device is configured to be connected to a test apparatus (not shown in the figures) for testing the integrated electronic device that also includes integrated optical elements such as a photonic chip, and thus it is provided with optical components designated for the above test. This type of probe head is also called an optoelectronic probe head.

[0045] As shown in FIGS. 2A and 2B, the probe head 10 includes a plurality of contact probes 11 configured to make electrical and mechanical contact with the contact pads 12a of the device under test 13. The plurality of contact probes 11 are in that case a plurality of components designated to perform an electrical test of the device under test 13, and as is known in the art, they can be divided into ground probes, power probes, and probes designated to transmit operating signal I / O between the device under test 13.

[0046] In particular, the contact probe 11 includes a body 11' that extends vertically along the longitudinal axis H-H between a first end 11a and a second opposite end 11b. The first end 11a is configured to contact an interface board (not shown in the figure), such as an interposer or a printed circuit board (PCB), that is interfaced with the probe head 10, while the second end 11b is configured to contact the contact pad 12a of the device under test 13.

[0047] That is, according to the present invention, the contact probe 11 is a vertical probe having a substantially vertical body 11' that can bend, for example, when contacting the device under test 13, and the probe head 10 is thus a vertical probe head.

[0048] The probe head 10 thus includes at least one guide 20 having a plurality of guide holes 20h for slidably accommodating a plurality of contact probes 11. By way of example, the guide 20 may be made of a ceramic material, as is known in the art.

[0049] In one embodiment of the present invention, the guide 20 is a lower guide, and the probe head 10 further includes an upper guide 30 having a plurality of guide holes 30h corresponding to the plurality of guide holes 20h for slidably accommodating a plurality of vertical contact probes 11.

[0050] To perform an optical test of a plurality of optical components integrated within the device under test 13, the probe head 10 includes at least one test optical signal distribution element 50 configured to transmit a test optical signal to the device under test 13. As defined below, in one embodiment of the present invention, the test optical signal distribution element 50 is connected to the lower guide 20.

[0051] It can be immediately recognized that a specific form of the test optical signal distribution element 50 is not a limiting factor within the scope of protection of the present invention, and that the optical signal distribution element 50 can be associated with the lower guide 20 in different ways.

[0052] Specifically, the test optical signal distribution element 50 is a waveguide, and in particular, includes a plurality of waveguides configured to transmit a test optical signal from a test device (not shown in the figure) to the device under test 13.

[0053] For example, as shown in FIG. 2A, the test optical signal distribution element 50 is an optical fiber 50f, and on the surface of the test optical signal distribution element 50 facing the device under test 13, an array of optical fibers 50f that are aligned with and terminated at the ends of the fibers may be provided. In this case, the test optical signal distribution element 50 extends vertically inside the probe head, that is, along a vertical axis that is substantially parallel to the axis z of the reference system of the figure, so that the extension of the optical fiber 50f can be traced.

[0054] In the embodiment of FIG. 2B, the test optical signal distribution element 50, instead, has a substantially horizontal extension and is a body made of a plastic or glass material and having a flow path therein with a refractive index changed with respect to the material, and thus, as will be described in detail below, a body that forms a path designated to transmit light (which, furthermore, ensures excellent positioning accuracy), may be provided. Furthermore, many other suitable configurations are possible, and what is important is that the test optical signal distribution element 50 is configured to transmit an optical signal from the probe head 10 towards the device under test 13, and in particular, towards its optical interface 12b.

[0055] Next, referring to FIGS. 2A and 2B, the probe head 10 includes a storage element or housing 40 configured to support the lower guide 20 and the upper guide 30. In particular, the storage element 40 is disposed between the lower guide 20 and the upper guide 30. As can be seen in FIGS. 2A, 2B, and 3, the storage element 40 houses at least one part of the contact probe 11 and provides a rigid support structure for the probe head 10 as a whole.

[0056] The storage element 40 thus functions as a support element for the probe head 10, and the lower guide 20 and the upper guide 30 are associated therewith.

[0057] According to the present invention, the storage element 40 comprises a first part 40a and a second part 40b that can be moved relative to the first part 40a.

[0058] In one embodiment of the present invention, for example, as shown in FIG. 4, the storage element 40 comprises at least one deformable arm 41 connecting the first part 40a and the second part 40b to each other. For example, in a non-limiting embodiment of the present invention, a plurality of deformable arms 41 may be provided at the four vertices of the storage element 40 and configured to connect the first part 40a to the second part 40b. For example, eight arms 41 may be provided, two for each vertex, and the arms may extend in pairs from the vertices and be separated by a void space. The arms 41 are shaped to be flexible, and the shape of the arms 41 enables the desired movement of the second part 40b of the storage element 40 relative to the first part 40a, as will be described below.

[0059] In one embodiment of the present invention, the storage element 40 has an overall substantially rectangular shape, and the first part 40a is its fixed outer frame (i.e., it is the fixed peripheral part), and the second part 40b is its movable central part.

[0060] As described above, in the embodiment of the present invention represented in FIG. 5, the test optical signal distribution element 50 includes a main body 50' made of, for example, a glass material or a plastic material, and a plurality of optical waveguides 51 formed in the main body 50' and configured to guide light from a light source toward the device under test 13. The optical waveguide 51 terminates at a terminal 51' from which a suitable light beam is emitted toward the optical interface 12b of the device under test 13. The test optical signal distribution element 50 has a design configured to facilitate its integration and alignment inside the probe head 10, particularly the connection with the guide 20.

[0061] As an example, the thickness of the test optical signal distribution element 50 varies between 0.5 mm and 3 mm, although this thickness may not be limited to a specific value. As described above, further, the form of the test optical signal distribution element 50 varies depending on the necessity and / or situation, for example, based on the position of the optical interface 12b and / or the electrical contact pads 12a of the device under test 13. Thus, the form simply shown and represented in the figure may not solely limit the scope of the present invention.

[0062] Furthermore, means such as a cable 52 are provided, which is configured to transmit an optical signal from the test device to the test optical signal distribution element 50, for example, a cable connecting the test device to the test optical signal distribution element 50, wherein the cable 52 includes an optical fiber therein and, optionally, is configured to carry an electrical signal. In one embodiment, the test optical signal distribution element 50 is connected to a component 53 including means for connecting to the optical fiber of the cable 52 and electronic means (e.g., a PCB board) for connecting and managing the electrical cable coming from the cable 52.

[0063] In an embodiment of the present invention, the test optical signal distribution element 50 is configured to couple light through the grating coupler of the device under test 13. In this case, the optical interface 12b of the device under test 13 includes a grating 12r configured to guide incident light into the waveguide of the device under test 13. During the test, the waveguide of the test optical signal distribution element 50 is located above the grating 12r, as schematically shown in FIGS. 2A and 2B, to which reference is made again here. This optical coupling configuration is advantageous because it enables direct testing on the wafer without the need to integrate a plurality of individual devices integrated on the wafer.

[0064] However, it can be recognized that the present invention is not limited by the structure and specific operation of the test optical signal distribution element 50, and may be a waveguide of any structure configured to couple light into the device under test according to any suitable configuration according to the necessity and / or situation. Similarly, the present invention is not limited by a specific optical coupling mode with the device under test.

[0065] Advantageously, according to the present invention, in order to obtain a desired optical alignment, the test optical signal distribution element 50 is configured to be associated with and moved integrally with the second part 40b of the storage element 40.

[0066] In the context of the present invention, the term "associated" can be recognized to mean that the test optical signal distribution element 50 is physically associated with the storage element 40, for example, connected by any suitable mode, and not necessarily directly connected, but indirectly connected through, for example, a further component of the probe head 10.

[0067] More particularly, preferably, the probe head 10 includes moving means 60 configured to move the second part 40b relative to the first part 40a thereof, in order to enable optical coupling of the emitted light by the test optical signal distribution element 50 associated with the second part 40b of the storage element 40.

[0068] In this way, the moving means 60 moves the test optical signal distribution element 50 (through the movement of the second part 40b), and thus enables the alignment of the test optical signal distribution element 50 with respect to the optical interface 12b of the device under test 13 (in particular, at least in the x-y plane according to the reference system of the figure, i.e., in a plane parallel to the plane in which the device under test 13 is located).

[0069] Referring again to FIG. 4, in one embodiment of the present invention, the moving means 60 is disposed within a specific housing sheet 40s formed within the first part 40a of the storage element 40.

[0070] Thanks to this architecture, stable alignment of the light emitted by the test optical signal distribution element 50 with respect to the optical interface 12b of the device under test 13 can be obtained in a simple manner.

[0071] In a preferred embodiment of the present invention, the test optical signal distribution element 50 is connected to the lower guide 20, which is then associated with the storage element 40 via the lower guide 20.

[0072] As shown in FIG. 4 and as detailed in FIG. 6, in one embodiment of the present invention, the lower guide 20 is not a single piece, but rather at least a first guide portion 20a connected to the first part 40a of the storage element 40, and a second guide portion 20b connected to the second part 40b of the storage element 40 and configured to move together with the second part 40b, in particular for the action of the operation of the moving means 60. In this way, further, the lower guide 20 includes a fixed portion, i.e., the first guide portion 20a connected to the fixed portion of the storage element 40 (e.g., via a screw 26 passing through a hole 27 formed within the first guide portion 20a), and a movable portion, i.e., the second guide portion 20b connected to the movable portion of the storage element 40 (still via a suitable fixing screw).

[0073] In one embodiment of the present invention, the second movable guide portion 20b includes a first guide portion 20b' including a guide hole 20h for accommodating the contact probe 11, and a second guide structure 20b" configured to accommodate the test optical signal distribution element 50, wherein the second guide structure 20b" is structurally independent of the first guide structure 20b'.

[0074] In the context of the present invention, the term "structurally independent" means that the two guide structures 20b' and 20b" are not initially fixedly attached to each other, but they maintain their own structural independence, that is, it can be recognized that they are initially made of two pieces (for example, two separate ceramic pieces). The term "structurally independent" thus means that the two guide structures 20b' and 20b" are initially made as separate parts.

[0075] In this way, the lower guide is divided into three guides, namely, a first guide portion 20a that is fixed (i.e., fixed to the outer frame 40a of the storage element 40), and a first guide structure 20b' and a second guide structure 20b" that are movable, that is, they are fixed to the movable core 40b of the storage element 40.

[0076] In this embodiment, both the guide structures 20b' and 20b" are attached to the second portion 40b of the storage element 40 and move integrally together. In one embodiment, the first guide structure 20b' is preferably shaped to leave a space for accommodating the second guide structure 20b", that is, the second guide structure 20b" can be accommodated during the shaping of the first guide structure 20b'.

[0077] That is, in particular, referring to FIGS. 6 and 7, and FIG. 8A (which represents a simplified view of FIG. 7 showing only the lower guide), in one embodiment of the present invention, the lower guide 20 comprises a static part (i.e., the first part 20a) and a dynamic part. The dynamic part is represented by a part 20b that includes a guide structure 20b' for accommodating the guide hole 20h for the contact probe 11 and a guide structure 20b" for accommodating the test optical signal distribution element 50, and the plurality of guide structures together form the second guide part 20b. In this embodiment, the test optical signal distribution element 50 is associated with the second guide structure 20b" of the second guide part 20b and is connected to an independent support of the lower guide 20, while the contact probe 11 is associated with the first guide structure 20b' that accommodates the guide hole 20h. That is, the test optical signal distribution element 50 is connected to its own support ceramic, which facilitates its alignment with the contact probe 11 as will be described below.

[0078] In this embodiment, the moving element 60 is configured to move the second part 40b and thus also the second guide part 20b. In this embodiment, both the first guide structure 20b' and the second guide structure 20b" are moved by the moving means 60, so that the contact probe 11 and the test optical signal distribution element 50 are moved integrally with each other, that is, they undergo the same displacement. In this way, the optical alignment movement of the test optical signal distribution element 50 results in a similar movement of the contact probe 11, which does not affect the electrical and mechanical contacts made thereby in any way and maintains the electrical and mechanical performance of the probe head 10 unchanged. The contact probe 11 is thus associated with the second movable part 40b of the storage element 40 and is configured to move integrally with the second part 40b and the test optical signal distribution element 50.

[0079] In this embodiment, the stationary first guide part 20a instead functions substantially as the lower cover element of the probe head 10.

[0080] In an alternative embodiment of the present invention shown in FIG. 8B, only the test optical signal distribution element 50 is movable, while the contact probe 11 always remains stationary. For example, in the embodiment of FIG. 8B (where only the lower guide is shown for simplicity), the contact probe 11 is housed within a first guide portion 20a (which is attached to a first portion 40a of the storage element 40 and has a guide hole 20h), and the test optical signal distribution element 50 is housed (connected, for example, adhesively) within a second guide portion 20b which is connected (for example, via a fixing screw) to a second portion 40b of the storage element 40 without further division of the lower guide 20. In this case, it can be said that there is no longer a first guide structure 20b' for housing the contact probe 11, while the second movable guide portion 20b corresponds to a second guide structure 20b", and thus, in this embodiment, only the first and second guide portions 20a and 20b are referred to. As described above, the first guide portion 20a is preferably shaped to enable it to house the second guide portion 20b.

[0081] In this embodiment, the contact probe 11 is thus associated with the first portion 40a of the storage element 40 and is configured to remain stationary during the movement of the second portion 40b of the storage element 40. In particular, the contact probe 11 is associated with the first portion 40a of the storage element 40 via the first guide portion 20a, and the test optical signal distribution element 50 is connected to the second portion 40b of the storage element 40 via the second guide portion 20b.

[0082] The storage element 40 has a free space G in a zone of the guide portion 20a where a guide hole 20h (usually within the central zone) is present to preferably enable housing of the contact probe 11.

[0083] Other configurations are possible in which the probe head 10 is configured such that the moving means 60 moves only the second guide structure 20b", and it is also possible to provide a case in which the test optical signal distribution element 50 is not associated with the guide but is directly connected to the storage element 40, particularly to its movable part.

[0084] Generally, the first guide portion 20a remains stationary, while the second guide portion 20b is made dynamic and movable by the moving means 60. In one embodiment, the second guide portion 20b is the movable central core of the probe head 10 to which the second part 40b of the storage element 40 and the test optical signal distribution element 50 are also fixed. In this way, in order to obtain the desired optical alignment, the test optical signal distribution element 50 can be accurately moved, for example, based on a standard spiral routine.

[0085] As described above, when it is also preferable to facilitate its association and alignment within the probe head 10 by providing the test optical signal distribution element 50 with its own guide (for example, strictly speaking, the second guide structure 20b", or more generally, the second guide portion 20b), the test optical signal distribution element 50 can be directly associated with the storage element 40, and the guide 20 can comprise only the first fixed guide portion 20a.

[0086] In one embodiment of the present invention, the upper guide 30 is instead made of a single piece, and the single piece comprises a guide hole 30h and an alignment hole, as will be described below.

[0087] The probe head 10 of the present invention thus comprises a monolithic housing having an outer frame (which is its first part 40a) for statically fixing to the mechanism of the probe head 10, and a centrally movable part (or movable central core, which is its second part 40b) connected to the outer frame by a deformable element having flexibility and elasticity, such as an arm 41, which can have any number and any form. The second movable part 40b is controlled by moving means 60 arranged in a housing sheet 40s formed within the first part 40a.

[0088] In one embodiment of the present invention, the moving means 60 comprises at least two piezoelectric transducers, each of the piezoelectric transducers being configured to effect a linear movement in the direction of the second part 40b of the storage element 40 (in particular, one of the directions x and y according to the reference system of the figure).

[0089] Obviously, within the scope of the present invention, other suitable moving means, not limited to only piezoelectric transducers, are also included, while such embodiments are considered preferable because piezoelectric transducers make it possible to obtain fine adjustment of the movement in a simple manner. In one embodiment, the piezoelectric transducer can effect a movement of 5 μm with an accuracy of 10 nm.

[0090] As shown in the accompanying drawings, in one embodiment, the test optical signal distribution element 50 is connected to a surface Fa of the lower guide 20, the surface Fa facing the device under test 13.

[0091] In a preferred embodiment of the present invention, the test optical signal distribution element 50 is adhered to the lower guide 20 (in particular, to its surface Fa). For this reason, referring to FIGS. 9A to 9C, the second guide structure 20b” designated to accommodate the test optical signal distribution element 50 includes a plurality of grooves 25, and the guide region occupied by the plurality of grooves forms an adhesive substrate. The grooves 25 are filled with a resin or other suitable adhesive 25g to enable the test optical signal distribution element 50 to be fixed to the lower guide 20 (in particular, to the second guide structure 20b”).

[0092] As described above, the storage element 40 is not limited by a specific form, and various different forms can be within the scope of the present invention. What is important is that the storage element 40 is such that the mobility of a part thereof is ensured by the moving element 60 accommodated therein (for example, particularly, by a suitable combination of the form and material used for the plurality of connecting arms 41 between its first part 40a and its second part 40b). For this purpose, the embodiments of FIGS. 10A and 10B are shown only as examples of different forms of the plurality of arms 41 that can ensure the desired elasticity of the connection between the fixed part and the movable part, and can be compared.

[0093] An efficient alignment system is provided that can be easily used in the assembly process of the probe head 10 to align the test optical signal distribution element 50 with the contact probe 11, and thus accurately align the probe head 10 with the layout of the device under test.

[0094] In particular, referring to FIGS. 11A and 11B next, the test optical signal distribution element 50 includes a first alignment hole 50al, the second guide structure 20b” that is structurally independent from the first guide structure 20b’ includes a second alignment hole 20al, and the upper guide 30 includes a corresponding third alignment hole 30al.

[0095] Preferably, the alignment holes 20al, 30al, and 50al are arranged and configured to enable the passage of a plurality or one alignment pin 70 to ensure the mutual alignment between the contact probe 11 housed in the first guide structure 20b' and the test optical signal distribution element 50 connected to the second guide structure 20b'' of the lower guide 20 when the centers of the alignment holes of the respective components are aligned along the same predetermined axis (in particular, along a vertical axis parallel to the axis H-H).

[0096] That is, when the respective alignment holes of the lower guide 20 (in particular, the second guide structure 20b''), the test optical signal distribution element 50, and the upper guide 30 are aligned with each other along the defined axis (and the above alignment is obtained by inserting the alignment pin 70), an accurate alignment and positioning of the test optical signal distribution element 50 in the probe head 10 (in particular, in the plane x-y) can be obtained, which can be fixed to the storage element, for example, via suitable fixing screws.

[0097] As described above, the upper guide 30 is made of a single piece. In this way, the upper guide 30 houses both the plurality of guide holes 30h designated to accommodate the plurality of contact probes 11 and the plurality of alignment holes 30al within a single piece.

[0098] In this way, it is possible to simply obtain an accurate mutual alignment between the test optical signal distribution element 50 and the guide hole 20h that houses the contact probe 11 by shifting from a spatial search routine of 20 - 50 μm to a search with a maximum width of 5 μm or even smaller.

[0099] That is, the alignment holes 20al, 30al, and 50al are arranged and configured such that when the centers of the alignment holes 50al of the test optical signal distribution element 50 are aligned with the centers of the corresponding alignment holes 20al of the second guide portion 20b and the centers of the corresponding alignment holes 30al of the upper guide 30, the passage of a plurality of alignment pins 70 is enabled to ensure the mutual alignment between the contact probe 11 and the test optical signal distribution element 50. The plurality of alignment holes through which a single pin 70 passes constitute a group of a plurality of corresponding aligned alignment holes.

[0100] In one embodiment of the present invention, the plurality of alignment holes are obtained by laser drilling with an accuracy of less than 3 μm, and thus the alignment accuracy is also very high.

[0101] Once the alignment pins 70 are inserted into all the specific plurality of alignment holes, the test optical signal distribution element 50 is completely aligned with all the other components of the probe head 10. Once aligned, the test optical signal distribution element 50, particularly its support to which the test optical signal distribution element 50 is adhered, is fixed to the storage element 40 via fastening screws passing through the respective fastening holes 80 formed in the lower guide. As described above, the potential alignment error between these components of the probe head 10 is equal to the accuracy of the forming process of the plurality of alignment holes, for example, via laser, and is generally less than 3 μm, and thus very low, thereby minimizing the subsequent optical alignment routine of the test optical signal distribution element 50.

[0102] Furthermore, in order to ensure accurate positioning along the vertical axis (i.e., along the axis z in the reference system of the figure), in one embodiment of the present invention, at least one spacer element 90 is provided between the storage element 40 and the second guide structure 20b”, and the spacer element 90 is removable to enable adjustment of the distance between the test optical signal distribution element 50 (thus, the outlet of the waveguide) and the device under test 13. Any suitable number of spacer elements 90 in any suitable form can clearly be used, but FIG. 12 shows a probe head 10 including a single spacer element 90.

[0103] As an example, the spacer element 90 may be made of steel or polyamide material, although other materials are clearly possible.

[0104] The spacer element 90 is thus arranged between the storage element 40 and the lower guide 20 and corresponds to a calibrated thickness (e.g., 25 or 30 μm) that can be removed when necessary to ensure adjustment of the distance along the axis z as described above.

[0105] Furthermore, it is possible to perform further fine vertical calibration by calibrated lapping of the contact probe 11.

[0106] Thanks to the vertical calibration described above, the distance between the outlets of the plurality of waveguides is approximately equal to that obtained by adding a working overdrive to the positioning requirements of the test optical signal distribution element 50.

[0107] In summary, the present invention provides a probe head having a plurality of vertical probes with a pair of guides in which storage elements (also called housings) of these plurality of vertical probes are arranged therebetween, and the vertical probe head technology is particularly combined with the presence of optical elements (especially waveguides) inside the probe head associated with the lower guide and for testing a plurality of devices including a photonic integrated circuit. The optical elements are integrated within the probe head to form a simple and compact structure. In particular, the storage element includes a fixed part (e.g., an external frame) and a movable part (e.g., a central core), and at least the waveguide for optical testing is provided with a movable part connected via a specified ceramic support. Simple moving means such as a piezoelectric transducer moves the movable part to obtain a fine and accurate alignment of the optical element with respect to the optical interface of the device under test. In this way, both the contact probe and the waveguide are associated with the same storage element of the probe head, and the movement of the movable part of the storage element is only necessary to obtain an optical alignment and to obtain a compact structure, and enables the use of the vertical probes housed within the guides and within the storage element. The designed architecture further enables a simple relative alignment between the contact probe and the optical element, and a simple adjustment of the distance in the vertical direction, by simply moving the ceramic support of the waveguide.

[0108] Therefore, it is possible to test optoelectronic devices via vertical probes without the assistance of complex and expensive precision mechanisms.

[0109] Advantageously, according to the present invention, there is provided an optoelectronic probe head including a plurality of optical components for optical testing of a device, enabling a very simplified alignment of the optical components, and a plurality of components are all integrated in a compact structure that enables the use of vertical probes.

[0110] In particular, preferably, the optical elements integrated within the probe head are associated with their storage elements, achieving a very compact structure without the need to introduce specific mechanical support arms for holding and moving said optical elements, thus simplifying the mechanical structure of the probe head and optimizing the space.

[0111] The alignment of the waveguide with respect to the optical interface of the device under test is really simple and, without relying on expensive mechanisms, only requires the movement of the movable part of the housing, for example, by means of a pair of piezoelectric transducers, without sacrificing the simplicity and compactness of the overall structure.

[0112] Preferably, as described above, the probe head of the present invention houses a vertical contact probe, i.e., a contact probe having a body that extends substantially vertically, configured to slide within the guide holes of at least one guide and bend while in contact with the device under test, with both ends usually being free. Thus, for example, it is possible to use very short contact probes to limit the self-inductance phenomenon and perform tests on high-frequency devices (for example, perform electrical tests up to GHz frequencies), there is a greater degree of freedom in choosing the layout, and greatly improved performance can be obtained.

[0113] Furthermore, the relative alignment between the contact probe and the optical components is very accurate and simple thanks to the possibility of moving the support of such optical components before fixing it with reference to the alignment holes.

[0114] The excellent mutual alignment between the probe and the waveguide means a short optical coupling routine, which brings a considerable advantage in terms of test time.

[0115] Furthermore, the possibility of accurately calibrating the vertical distance between the optical element and the device under test is added to all of the above.

[0116] Therefore, the probe head of the present invention combines a compact structure with ease and stability of alignment of the optical components in all of a plurality of spatial directions with respect to the device under test and with respect to the contact probes designated for electrical testing.

[0117] Therefore, the described probe head solves the technical problem of the present invention and realizes all of the various advantages described above.

[0118] An important application field of the probe head of the present invention is the field of high-speed data transmission and data centers that require reduced energy consumption.

[0119] Obviously, those skilled in the art can make numerous modifications and variations to the above probe head to meet non-specific and specific requirements, all of which are included within the scope of protection of the present invention defined by the following claims.

Claims

1. A plurality of contact probes (11), which are vertical contact probes, each having a main body configured to be in electrical and mechanical contact with a contact pad (12a) of a device under test (13) and extending along a longitudinal axis (H-H) between a first end (11a) and a second end (11b); At least one guide (20) having a plurality of guide holes (20h) for slidably accommodating the plurality of contact probes (11); A storage element (40) configured to support the guide (20) and accommodate at least one portion of the plurality of contact probes (11), the storage element (40) comprising a first portion (40a) and a second portion (40b) movable relative to the first portion (40a); Moving means (60) configured to move the second portion (40b) of the storage element (40) relative to the first portion (40a); and At least one test optical signal distribution element (50) configured to transmit a test optical signal to the device under test (13), wherein the test optical signal distribution element (50) is associated with the second portion (40b) of the storage element (40) and is configured to be moved integrally with the second portion (40b) by the moving means (60), and the moving means (60) is configured to enable alignment of the test optical signal distribution element (50), a probe head (10) for a test apparatus of an electronic device.

2. The probe head (10) according to claim 1, wherein the guide (20) is configured as a first guide portion (20a) connected to the first portion (40a) of the storage element (40) and a second guide portion (20b) connected to the second portion (40b) of the storage element (40) and configured to move with the second portion (40b) of the storage element (40).

3. The probe head (10) according to claim 1, wherein the plurality of contact probes (11) are associated with the first portion (40a) of the storage element (40) and are configured to remain stationary during movement of the second portion (40b) of the storage element (40).

4. The guide (20) is configured as a first guide portion (20a) connected to the first portion (40a) of the storage element (40), and a second guide portion (20b) connected to the second portion (40b) of the storage element (40) and configured to move together with the second portion (40b) of the storage element (40). Further, the plurality of contact probes (11) are associated with the first portion (40a) of the storage element (40) via the first guide portion (20a), and the test optical signal distribution element (50) is associated with the second portion (40b) of the storage element (40) via the second guide portion (20b). The probe head (10) according to claim 3.

5. The plurality of contact probes (11) are further associated with the second portion (40b) of the storage element (40) and are configured to move integrally with the second portion (40b) and the test optical signal distribution element (50). The probe head (10) according to claim 1.

6. The guide (20) is configured as a first guide portion (20a) connected to the first portion (40a) of the storage element (40), and a second guide portion (20b) connected to the second portion (40b) of the storage element (40) and configured to move together with the second portion (40b) of the storage element (40). The second guide portion (20b) includes a first guide structure (20b') including the plurality of guide holes (20h) for accommodating the plurality of contact probes (11), and a second guide structure (20b'') configured to accommodate the test optical signal distribution element (50), and the second guide structure (20b'') is structurally independent of the first guide structure (20b'). The probe head (10) according to claim 5, comprising a second guide structure (20b'').

7. The moving means (60) includes at least two piezoelectric transducers, and each of the piezoelectric transducers is configured to cause linear movement of the second portion (40b) of the storage element (40) in a specific direction (x, y). The probe head (10) according to claim 1, comprising at least two piezoelectric transducers.

8. The test optical signal distribution element (50) is the probe head (10) according to claim 1, which is connected to the surface (Fa) of the guide (40) facing the device under test (13).

9. The test optical signal distribution element (50) is the probe head (10) according to claim 8, which is adhered to the surface (Fa) of the guide (20).

10. The probe head (10) according to claim 1, wherein the guide (20) is a lower guide, and the probe head (10) further comprises an upper guide (30), and the storage element (40) is arranged between the lower guide (20) and the upper guide (30).

11. The guide (20) is composed of a first guide portion (20a) connected to the first portion (40a) of the storage element (40), and a second guide portion (20b) connected to the second portion (40b) of the storage element (40) and configured to move together with the second portion (40b) of the storage element (40). The test optical signal distribution element (50) is provided with a first alignment hole (50al), the second guide portion (20b) of the lower guide (20) is provided with a second alignment hole (20al), and the upper guide (30) is provided with a third alignment hole (30al). The first alignment hole (50al), the second alignment hole (20al), and the third alignment hole (30al) are arranged and configured to enable the passage of a plurality of alignment pins (70) to ensure the mutual alignment between the plurality of contact probes (11) and the test optical signal distribution element (50) connected to the second guide portion (20b) of the lower guide (20). When the center of the first alignment hole (50al) of the test optical signal distribution element (50) is aligned along a respective predetermined axis with the center of the corresponding second alignment hole (20al) of the second guide portion (20b) and the center of the corresponding third alignment hole (30al) of the upper guide (30). The probe head (10) according to claim 10.

12. The plurality of alignment holes are obtained by laser drilling with an accuracy of less than 3 μm. The probe head (10) according to claim 11.

13. The probe head (10) according to claim 10, wherein the upper guide (30) is made of a single piece.

14. The probe head (10) according to claim 1, wherein the test optical signal distribution element (50) may include a glass or plastic body (50') and a plurality of waveguides (51) formed in the glass or plastic body (50') and configured to guide light from a light source toward the device under test (13).

15. The probe head (10) according to claim 1, wherein the test optical signal distribution element (50) is configured to couple light through a grating coupler of the optical interface (12b) of the device under test (13).

16. The probe head (10) according to claim 1, comprising at least one spacer element (90) disposed between the storage element (40) and the guide (20), the spacer element (90) being removable to enable adjustment of the distance between the test optical signal distribution element (50) and the device under test (13).

17. The probe head (10) according to claim 1, wherein the storage element (40) comprises at least one deformable arm (41) connecting its first part (40a) and its second part (40b) to each other.

18. The probe head (10) according to claim 1, wherein the first part (40a) of the storage element (40) is a peripheral part of the storage element (40), and the second part (40b) of the storage element (40) is a central part of the storage element (40).

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