Testing method and testing system

Abstract

The present disclosure relates to a method (300) of electrically testing an electronic device, the method (300) including: providing (310) a test probe, wherein the test probe comprises a deformable contact structure with an electrically conductive portion; bringing (320) the deformable contact structure and an electrical contact of the electronic device into contact with one another to cause a deformation of the deformable contact structure such that the electrically conductive portion at least partially conforms to a shape of the electrical contact of the electronic device; and causing (330) a flow of electrical current into the electrical contact of the electronic device through the electrically conductive portion of the deformable contact structure to perform an electrical testing of the electronic device.

Description

TESTING METHOD AND TESTING SYSTEMTechnical Field

[0001] The present disclosure relates generally to a testing system for carrying out electrical testing of a device (e.g., an electronic module), and to methods thereof (e.g., a method of carrying out electrical testing of a device).Background

[0002] In general, devices including electronic circuits are subjected to various tests to verify their correct functioning and implement corrective measures or discard defective modules if necessary. Among the various types of tests, electrical testing allows verifying the electrical connections in the circuit and the operation of the circuit when powered up. For electrical testing, temporary electrical connections are established with corresponding contact locations of the device. The tests may be performed either at the wafer-level (illustratively, when the integrated circuits are still on wafer) or at the package-level (illustratively, after packaging of the integrated circuits). In some scenarios, testing at the package level may be preferred as it allows evaluating the actual device that will be delivered to a customer. In view of the constant trend towards miniaturization of electronic devices and components, the package density is correspondingly increased, thus reducing the space available for establishing the temporary electrical connections for testing the circuits. There is thus a need for improved ways of carrying out electrical testing of electronic devices.Brief Description of the Drawings

[0003] In the drawings, like reference characters generally refer to the same parts throughout the different views. The drawings are not necessarily to scale, emphasis instead generally being placed upon illustrating the principles of the invention. In the following description, various aspects of the invention are described with reference to the following drawings, in which:FIG.1A shows a contact structure in a schematic representation, according to various aspects;FIG. IB shows a contact structure disposed on a substrate in a schematic representation, according to various aspects;FIG.1C shows a contact structure monolithically integrated with a substrate in a schematic representation, according to various aspects;FIG. ID shows a contact structure monolithically integrated with a substrate and disposed on a further substrate in a schematic representation, according to various aspects;FIG.2A to FIG.2C show various configurations of a test probe including a plurality of contact structures in a schematic representation, according to various aspects;FIG.3 shows a schematic flow diagram of a method of carrying out electrical testing of an electronic device according to various aspects;FIG.4 shows a testing system including a test probe and an electronic device under test in a schematic representation, according to various aspects;FIG.5A to FIG.5G show various configurations of contact structures in a schematic representation, according to various aspects;FIG.6A to FIG.6C show various configurations of contact structures having a deformable portion including a plurality of different materials in a schematic representation, according to various aspects;FIG.7A and FIG.7B show contact structures including a channel extending therethrough in a schematic representation, according to various aspects; andFIG.7C and FIG.7D show test probes including channels extending through the substrate in a schematic representation, according to various aspects.Description

[0004] The following detailed description refers to the accompanying drawings that show, by way of illustration, specific details and aspects in which the invention may be practiced. These aspects are described in sufficient detail to enable those skilled in the art to practice the invention. Other aspects may be utilized and structural, logical, and electrical changes may be made without departing from the scope of the invention. The various aspects are not necessarily mutually exclusive, as some aspects may be combined with one or more other aspects to form new aspects. Various aspects are described in connection with methods and various aspects are described in connection with devices (e.g., a contact structure, a test probe, a testing system). However, it is understood that aspects described in connection with methods may similarly apply to the devices, and vice versa.

[0005] In general, electrical testing of integrated circuits plays an important role to assist manufacturers of electronic devices in identifying defective components before shipping a product to the customers. Electrical testing allows determining in general the response of the electronic device to a supplied current, e.g. whether the electronic device operates correctly,whether electrical connections are working properly, and the like. Electrical testing may allow the manufacturer to adapt fabrication processes or parameters to reduce (or ideally eliminate) the occurrence of defects. Electrical testing, in combination with other types of tests (e.g., resistance to temperature variations, resistance to mechanical shocks, etc.) allows thus evaluating the overall production quality and adjust the manufacturing cycle.

[0006] As semiconductor technology progresses, integrated circuits become more and more miniaturized, and accordingly the dimensions of electrical contacts (e.g., terminals, pads) on a chip become smaller and smaller. Temporarily electrical contacting of small modules such as chip-scale package (CSP) of CMOS sensors (where CMOS stands for Complementary Metal- Oxi de- Semi conductor), as an example, is thus becoming more challenging in view of the reduced dimensions of the dies, in particular considering multiple contacts and handling restrictions for certain surfaces.

[0007] In this context, so-called “pogo pins” are conventionally used for electrical testing of electronic devices. A pogo pin is a spring-loaded electrical connector that enables an electrical testing that is robust against manufacturing tolerances, such as height variations of solder balls, and may thus ensure flexible electrical connections for proper contacting of multiple contacts (e.g., in an array). However, the use of pogo pins may limit the packing density of the contacts available for carrying out the testing, due to the complex spring-loaded construction and the needed surrounding assembly. In addition, pogo pins may come with a high variation in contact force for low force small contacts. Therefore, when using pogo pins it may be challenging to properly contact a compact contact array such as a small ball grid array (BGA).

[0008] In this framework, the present disclosure may be based on the realization that rather than relying on mechanically complex spring-loaded contacts, a test probe for electrical testing may include flexible and deformable contact structures capable of undergoing a deformation when brought into contact with the terminals of the device under test. The deformation of the contact structures causes an electrically conductive portion of the contact structure to conform to the shape of the corresponding electrical contact of the device under test, thus providing a robust and reliable electrical connection even in presence of slight variations in the geometry of the electrical contacts (e.g., variations in shape, dimensions, position, etc.).

[0009] The present disclosure may be based on the realization that flexible and deformable contact structures may be fabricated in a simple and scalable manner compared to conventional testing pins, and further may be fabricated with miniaturized dimensions (e.g., at the nanometer level or micrometer level), thus enabling electrical testing of small and high-density contact arrays. Thus, instead of using a complex mechanical assembly of a spring-loaded conductivepin, the test probe proposed herein may make use of a deformable structure (e.g., an elastic structure) to enable a controlled and conformal contacting of multiple electrical contacts. The proposed approach allows miniaturizing the contacting mechanism as it does not rely on springs that would otherwise limit the miniaturization.

[0010] In addition, an array of flexible conductive structures may be formed and placed with high precision and in very small sizes. As an example, the contact structures may be formed using photolithographic processes, thus allowing a precise placement and a higher packing density of contacts. For example, the proposed contact structures may include an elastomer, which may be placed using a variety of processes, such as simple droplet dispensing or ink jetting to form spherical contacts, or replication, nano-imprinting, or thermal imprinting for more complex and smaller structures. As these processes may be performed at sheet-level or wafer-level, this approach is highly scalable and allows for simple mass manufacturing of such contact structures. The test probe proposed herein may thus include very small contacts with a very tight pitch down to only a few micrometer in size or even below the micrometer level.

[0011] According to various aspects, a test probe for electrical testing of an electronic device may include a deformable contact structure (e.g., a plurality of deformable contact structures, e.g. elastically deformable contact structures), wherein the deformable contact structure includes an electrically conductive portion, and wherein the deformable contact structure is configured to deform when the deformable contact structure is brought into contact with an electrical contact of the electronic device to allow the electrically conductive portion to at least partially conform to a shape of the electrical contact.

[0012] Various aspects may be related to the use of the test probe for carrying out electrical testing of an electronic device (e.g., an optoelectronic device), e.g. of an electronic device including a ball grid array.

[0013] According to various aspects, a testing system for electrically testing an electronic device may include: a test probe comprising a deformable contact structure with an electrically conductive portion; a positioning system configured to hold the deformable contact structure and an electrical contact of the electronic device in contact with one another to cause a deformation of the deformable contact structure such that the electrically conductive portion at least partially conforms to a shape of the electrical contact of the electronic device; and a control circuit configured to cause a flow of electrical current into the electrical contact of the electronic device through the electrically conductive portion of the deformable contact structure to perform an electrical testing of the electronic device.

[0014] According to various aspects, a method of electrically testing an electronic device may include: providing a test probe, wherein the test probe includes a deformable contact structure with an electrically conductive portion; bringing the deformable contact structure and an electrical contact of the electronic device into contact with one another to cause a deformation of the deformable contact structure such that the electrically conductive portion at least partially conforms to a shape of the electrical contact of the electronic device; and causing a flow of electrical current into the electrical contact of the electronic device through the electrically conductive portion of the deformable contact structure to perform an electrical testing of the electronic device.

[0015] In a preferred configuration, a deformable contact structure may include an elastic bulk material such as an elastomer (e.g., poly dimethyl siloxane, PDMS) that may be conductive by itself or covered with a conductive layer. The conductive layer may include any suitable electrically conductive material, e.g. a metal, a metal alloy, a conductive metal oxide (e.g., indium tin oxide, ITO), a conductive polymer, etc. In some aspects, the conductive layer may be structured to create electrical traces. The contact structures may be provided either in a monolithic form, like a continuous structured layer of such a flexible material, or on a carrier substrate such as a printed circuit board (PCB), a glass wafer, a silicon wafer, and the like, for further electrical integration.

[0016] The combination of a predefined elastic structure (e.g., in a polymer such as PDMS, as an example) with an electrically conductive portion enables temporarily contacting arrays of electrical contacts down to the micrometer level. The proposed contact structures may be fabricated with higher manufacturing precision, placement accuracy, and packing density. Furthermore, it may be possible to integrate additional features directly in the elastic material, e.g. sealing areas in case of a vacuum socket design, thus enhancing the capabilities of the test probe.

[0017] FIG.1A to FIG.1D show a contact structure 100 in a schematic representation, according to various aspects. FIG.1 A to FIG. ID show possible configurations 100a, 100b, 100c, lOOd of the contact structure, which are collectively referred to as contact structure 100. The contact structure 100 may be an adapted configuration of a contact structure for use in a test probe for carrying out electrical testing of an electronic device (see also FIG.2 to FIG.4). A “contact structure” may also be referred to herein as contact element, or simply as contact. A “contact structure” adapted as proposed herein may also be referred to as deformable contact structure.

[0018] In general, the contact structure 100 may be deformable. Illustratively, the contact structure 100 may be a deformable contact structure capable of undergoing a deformation when a force is applied to it. Stated differently, the contact structure 100 may be configured to allow for a deformation of the contact structure 100 when a force is applied to the contact structure, e.g. when the contact structure 100 is brought into contact with an electrical contact of an electronic device under test.

[0019] The contact structure 100 may in general include a deformable portion 102 and an electrically conductive portion 104. The deformable portion 102 may be configured to deform upon application of a force (e.g., a compressive force) to cause a corresponding deformation of the contact structure 100. In an operation for electrical testing, the deformable portion 102 may be configured to deform upon the contact structure 100 entering / being in contact with an electrical contact of a device under test to allow the electrically conductive portion 104 to at least partially conform to the shape of the electrical contact. Stated differently, the deformable portion 102 may be configured to allow for a deformation of the of the contact structure 100 to cause a shape of the electrically conductive portion 104 to at least partially conform to the shape (e.g., the profile) of the electrical contact.

[0020] The contact structure 100 (e.g., the deformable portion 102) may thus be flexible to allow for a flexible adaptation of the contact structure 100 to the electrical contact of the device under test. In a preferred configuration, the contact structure 100 (e.g., the deformable portion 102) may be elastically deformable, e.g., may be configured to deform upon application of a force and to return to a non-deformed state when the force is no longer applied. An elastic deformation allows reusing the contact structure 100 (and a corresponding test probe) for multiple electrical testing processes. In some aspects, however, the contact structure 100 (e.g., the deformable portion 102) may be permanently deformable, e.g. may be configured to deform upon application of a force and remain in the deformed state even when the force is no longer applied. Illustratively, the contact structure 100 may undergo an inelastic deformation. This configuration may be provided, for example, for disposable test probes, which may be fabricated in mass production and relatively low cost when configuring the contact structures as proposed herein.

[0021] By way of illustration, the contact structure 100 may have a first shape when no force (e.g., no compressive force) is applied to the contact structure 100, e.g. when the contact structure 100 is not in contact with the electrical contact of the device under test. The first shape may be an original shape of the contact structure 100, e.g. a non-deformed shape or initial shape. The contact structure 100 may further have a second shape when a force (e.g., a compressiveforce) is applied to the contact structure 100, e.g. when the contact structure 100 is in contact with the electrical contact of the device under test. The second shape may illustratively be a deformed shape in which the contact structure 100 has a shape different from the original shape, e.g. a shape adapted to the electrical contact. The deformed (second) shape may vary depending on the force applied to the contact structure 100, e.g. the magnitude, the direction, etc., and may vary depending on the shape of the electrical contact against which the contact structure 100 is pressed.

[0022] In case of a contact structure 100 capable of elastic deformation, the contact structure 100 may be configured to return to the first (non-deformed) shape when the force is no longer applied, e.g. when the contact structure 100 is no longer in contact with the electrical contact of the device under test. In other aspects, the contact structure 100 may remain in the second (deformed) shape, or in another deformed shape different from the original shape, even after the force is no longer applied to the contact structure 100.

[0023] The contact structure 100 (e.g., the deformable portion 102) may thus include or be made of a material that allows for a deformation of the shape of the contact structure 100 and a corresponding conformal contact of the electrically conductive portion 104 with an electrical contact of a device under test. In a preferred configuration, the contact structure 100 (e.g., the deformable portion 102) may include or be made of a polymer material, e.g. a soft polymer. Polymer materials may enable a cost-effective and scalable fabrication of the contact structure 100 and corresponding test probe, and may be suitable to facilitate a deformation of the contact structure 100. For example, the contact structure 100 (e.g., the deformable portion 102) may include or be made of an elastomer. As exemplary materials, the contact structure 100 (e.g., the deformable portion 102) may include or be made of natural rubber, polyurethane, polybutadiene, neoprene, silicone, poly dimethyl siloxane (PDMS), polyethylene terephthalate (PET), and the like.

[0024] The electrically conductive portion 104 may have any suitable configuration to allow using the contact structure 100 for performing electrical testing of a device, e.g. any suitable configuration to allow establishing an electrically conductive connection with an electrical contact of the device under test. In a preferred configuration, the electrically conductive portion 104 may be distinct from the deformable portion 102. For example, the electrically conductive portion 104 may be or include an electrically conductive layer disposed on the deformable portion 102, e.g. in direct physical contact with the deformable portion 102. For example, the electrically conductive portion 104 may be or include an electrically conductive layer conformally formed on the deformable portion 102. In this configuration, the electricallyconductive portion 104 may include or may be made of any suitable electrically conductive material, e.g. a metal (such as gold), a metal alloy, an electrically conductive oxide (e.g., ITO), and the like. The use of a distinct portion, e.g. a distinct layer, allows a more flexible tailoring of the properties of the deformable portion 102 and electrically conductive portion 104. For example, the electrically conductive portion 104 may be a continuous layer. As another example, the electrically conductive portion 104 may be a layer including one or more empty portions (illustratively, one or more holes).

[0025] In other aspects, the electrically conductive portion 104 may be part of the deformable portion 102. In this configuration the deformable portion 102 may include or may be made of a material that is electrically conductive and allows the deformation of the contact structure 100 to provide the conformal contacting. For example, the deformable portion 102 may include the electrically conductive portion 104, and may include or may be made of an electrically conductive polymer such as polyacetylene or polyphenylene vinylene. As another example, the deformable portion 102 / electrically conductive portion 104 may include a base polymer that may be easily deformed and one or more doping elements that impart electrical conductivity to the base polymer, e.g. the deformable portion 102 / electrically conductive portion 104 may include electrically conductive particles embedded in a polymer matrix.

[0026] It is understood that the aspects described herein apply in relation to a “contact structure including an electrically conductive portion” apply in a corresponding manner both to the configuration in which the electrically conductive portion is distinct from the deformable portion, and to the configuration in which the deformable portion includes the electrically conductive portion.

[0027] The deformable contact structure 100 may have any suitable shape, as will be described in further detail in relation to FIG.5A to FIG.5G, and may in general be engineered according to the shape of the electrical contacts to be tested. As an exemplary configuration, which may allow a more uniform adaptation to the shape of the electrical contact, the contact structure 100 (e.g., the deformable portion 102) may have a dome-like shape, illustratively a hemispherical shape, as shown in FIG.1A to FIG. ID. As other examples, the contact structure 100 may have a pyramid shape, a cone shape, a cylindrical shape, an inverted-pyramid shape, etc.

[0028] In principle, a contact structure 100 configured as proposed herein may have any suitable dimensions, e.g. adapted according to the electrical contacts to be tested. The proposed approach is however particularly suitable to allow a miniaturization of the contact structure 100, thus allowing to provide a test probe with a high density of contact structures 100 (see also FIG.2A to FIG.2C). Thus, in a preferred configuration the contact structure 100 may havedimensions in the micrometer range, or even in the nanometer range. It is however understood that the aspects discussed herein may apply in a corresponding manner to contact structures having greater dimensions.

[0029] As a numerical example, the contact structure 100 may have a lateral extension 110 in the range from 100 nm to 500 pm, for example in the range from 1 pm to 100 pm, for example in the range from 5 pm to 50 pm, for example in the range from 10 pm to 20 pm. The lateral extension 110 may be a dimension of the contact structure 100 in the plane defined by a main surface of a corresponding test probe, e.g. the plane defined by a substrate on which the contact structure 100 is disposed. For example, the lateral extension 110 may be a width or a length of a base of the contact structure 100. In some aspects, the lateral extension 110 may be a diameter of the base of the contact structure 100.

[0030] As another numerical example, the contact structure 100 may have a height 112 (illustratively, a thickness) in the range from 100 nm to 500 pm, for example in the range from 1 pm to 100 pm, for example in the range from 5 pm to 50 pm, for example in the range from 10 pm to 20 pm. The height 112 may be a dimension of the contact structure 100 in a direction perpendicular to the plane defined by a main surface of a corresponding test probe, e.g. the plane defined by a substrate on which the contact structure 100 is disposed.

[0031] Considering in general a thin electrically conductive portion 104, or an electrically conductive portion 104 part of the deformable portion 102, such ranges for the lateral extension 110 and height 112 of the contact structure 100 may refer to ranges for the lateral extension and height of the deformable portion 102 of the contact structure 100.

[0032] With the proposed approach, the contacting of the electrical contacts may be achieved without the need for complex mechanical arrangements in the contact structure 100 or corresponding test probe. Illustratively, the proposed approach may be based on providing electrical contacting via causing a deformation (e.g., an elastic deformation) of the contact structure 100 itself, which leads to a conformal contact of the electrically conductive portion 104 with the electrical contact of the device under test. According to various aspects, the deformable contact structure 100 (and in a corresponding manner a test probe including a plurality of such contact structures 100) may be free of mechanical components, in particular the contact structure 100 (and test probe) may be free of a mechanical spring, which could otherwise limit the miniaturization of the contact structure 100.

[0033] According to various aspects, as shown in FIG. IB to FIG. ID, the contact structure 100 may further include a substrate 106, 108 or may be disposed on a substrate 106, 108. For example, as shown in the configuration 100b in FIG. IB, the deformable portion 102 and theelectrically conductive portion 102 may be disposed (e.g., formed) on a substrate 106. The substrate 106 may also be referred to herein as “carrier substrate”. The substrate 106 may include or may be made of any suitable material. For example, the substrate 106 may be a wafer, e.g. a silicon wafer or a glass wafer. As another example, the substrate 106 may be a printed circuit board (PCB). In some aspects, the substrate 106 may be a rigid substrate to facilitate the handling and placement of the contact structure 100 (and test probe). Furthermore, a rigid substrate may facilitate the integration of additional elements, e.g. further electrical integration.

[0034] In other aspects, as shown in the configuration 100c in FIG.1C, the deformable portion 102 may be monolithically formed with the substrate 108. In this configuration, the substrate 108 may be a substrate portion structured to define the deformable portion 102. The substrate portion 108 may thus include or may be made of the same material as the deformable portion 102. In an exemplary configuration, the substrate portion 108 may include or may be made a polymer, e.g. an elastomer, for example PDMS or PET. The substrate 108 may thus itself be deformable and flexible, e.g. elastically deformable, which may facilitate the conformal contacting when the contact structure 100 (and test probe) are brought in contact with the device under test. As a further exemplary configuration lOOd shown in FIG. ID, the contact structure lOOd may include the deformable portion 102 monolithically formed with the substrate portion 108, and may further include a (rigid) carrier substrate 106 on which the substrate portion 108 / deformable portion 102 are disposed.

[0035] In the following some aspects are described or illustrated for a first configuration in which a contact structure (or test probe) is disposed on a carrier substrate, or for a second configuration in which the deformable portion is monolithically formed with a substrate portion, or for a third configuration in which the deformable portion is monolithically formed with a substrate portion and further disposed on a (rigid) carrier substrate. It is however understood that the aspects described / illustrated in relation to one of the configurations may apply in a corresponding manner to the other two configurations, and vice versa.

[0036] In principle, a contact structure 100 as described herein may be fabricated using any suitable fabrication method. Considering the preferred configuration in which the contact structure 100 has nanometer or micrometer dimensions, possible fabrication methods may include droplet dispensing, ink jetting, replication, nano-imprinting, thermal imprinting, photolithography, and the like. For example, the contact structure 100 may be fabricated using wafer-level optics techniques. Wafer-level optics may be based on processes typical of semiconductor manufacturing, such as thin film deposition, lithography, etching, molding, imprinting, and the like. For example, a plurality of contact structures 100 may be fabricatedusing molds, thus enabling mass production. Wafer-level optics may allow producing components with a reduced footprint compared to other fabrication techniques.

[0037] As an example, a polymer (e.g., an elastomer) may be disposed on a substrate to form the deformable portion 102, e.g. via droplet dispensing to achieve a dome-like shape for the deformable portion 102, and subsequently a thin layer of electrically conductive material (e.g., a metal) may be formed (e.g., deposited and patterned) on the droplet to form the electrically conductive portion 104.

[0038] FIG.2A to FIG.2C show a test probe 200 including a plurality of contact structures 210. FIG.2A to FIG.2C show possible configurations 200a, 200b, 200c of the test probe, which is collectively referred to as test probe 200. The test probe 200 may include a plurality of contact structures 210 adapted as described herein for carrying out electrical testing of an electronic device. A “test probe” may also be referred to herein as “electrical test probe”, “testing tool”, “electrical testing tool”, “electrical probe system”, or “electrical prober”.

[0039] The contact structures 210 may be configured as the contact structure 100 described in relation to FIG.1A to FIG. ID, and may include a deformable portion 202 and an electrically conductive portion 204. In FIG.2A to FIG.2C a certain configuration of the contact structures 210 is shown (e.g., with dome-shape deformable portion 202, with the electrically conductive portion 204 as a layer disposed on the deformable portion 202, etc.). It is however understood that the aspects described in relation to FIG.2A to FIG.2C may apply to any suitable configuration of the contact structures 210, e.g. as discussed in FIG.1A to FIG. ID.

[0040] A test probe 200 may include any suitable number of contact structures 210, e.g. depending on the number of electrical contacts to be tested. As a numerical example a test probe 200 may include a number of contact structures 210 in the range from 1 to 10000 (ten thousand), for example a number of contact structures 210 in the range from 10 to 1000 (one thousand), for example a number of contact structures 210 in the range from 100 to 500.

[0041] In general, the contact structures 210 may have any suitable disposition in the test probe 200, and may be disposed according to a disposition of electrical contacts of an electronic device to be tested. Illustratively, the spatial arrangement of the contact structures 210 may be configured according to a spatial arrangement of the electrical contacts of the electronic device, e.g. the spatial arrangement of the contact structures 210 may correspond to the spatial arrangement of the electrical contacts. It is however understood that in principle it is not necessary that the contact structures 210 correspond exactly to the electrical contacts, e.g. in terms of quantity, spatial arrangement, etc., for carrying out the electrical testing, as it may besufficient that an adequate number of electrical contacts are reached by the contact structures 210.

[0042] According to various aspects, the contact structures 210 may be disposed in an array configuration. For example, the contact structures 210 may be disposed in a one-dimensional array, e.g. a row or a column. As another example, the contact structures 210 may be disposed in a two-dimensional array, e.g. a matrix, with a number N of rows and a number M of columns, where N and M are integer numbers greater than 1. In an exemplary configuration, the contact structures 210 may be disposed according to the disposition of electrical contacts in a corresponding ball grid array (BGA) of an electronic device to be tested.

[0043] As mentioned, the proposed approach allows for a miniaturization of the contact structures 210. Accordingly, the proposed approach allows obtaining a high density of contact structures 210. In various aspects, a distance between adjacent contact structures 210 (e.g., a center-to-center distance) may be in the range from 100 pm to 10 mm, for example in the range from 200 pm to 5 mm, for example in the range from 500 pm to 1 mm. Considering a periodic array of contact structures 210 the distance between adjacent contact structures 210 may be a pitch of the array (e.g., along one array direction, or along both array directions).

[0044] As discussed in relation to FIG. IB to FIG. ID, the deformable portion 202 of the contact structures 210 may be disposed on a carrier substrate 206 (as shown for the configuration 200a), e.g. configured as the carrier substrate 106 in FIG. IB, or may be monolithically formed with a substrate 208 (as shown for the configuration 200b), e.g. configured as the substrate portion 108 in FIG.1C. As a further exemplary configuration 200c, the test probe 200 may include contact structures 210 having a deformable portion 202 monolithically formed with a substrate portion 208, and further disposed on a carrier substrate 206.

[0045] In a simple configuration, the contact structures 210 may all have the same configuration, e.g. the same shape, the same dimension, the same type of materials, etc. In principle, however, it may be possible to vary one or more properties of the contact structures 210, e.g. to provide tailored patterns and properties according to the properties of a device to be tested. Thus, in some aspects, the test probe 200 may include contact structures 210 with different properties. For example, the test probe 200 may include a first contact structure with a first shape and a second contact structure with a second shape different from the first shape. The test probe 200 may further include a third contact structure with a third shape different from the first shape and second shape, etc. As another example, the test probe 200 may include a first contact structure with a first height and a second contact structure with a second height different from the first height. The test probe 200 may further include a third contact structurewith a third height different from the first height and second height, etc. The same may apply to a different lateral extension, e.g. a different diameter. As a further example, the test probe 200 may include a first contact structure with a first material and a second contact structure with a second material different from the first material (e.g., a different polymer, or a different electrically conductive material). The test probe 200 may further include a third contact structure with a third material different from the first material and second material, etc.

[0046] According to various aspects, the test probe 200 may further include electrical wiring coupled with the contact structures 210. The test probe 200 may illustratively include electrically conductive lines (e.g., connection lines, electrical traces) coupled with the electrically conductive portion 204 of the contact structures 210. The electrically conductive lines may be used to deliver electrical signals (e.g., a current, a voltage) to the electrically conductive portion(s) 204, e.g. the electrically conductive lines may couple the contact structures 210 with corresponding terminals at which the electrical signals may be provided. The electrically conductive lines (not shown in FIG.2A to FIG.2C) may be disposed on the substrate 206 or substrate portion 208 of the test probe 200, according to any suitable pattern that allows contacting the contact structures 210. According to various aspects, the electrically conductive lines may be formed while structuring the electrically conductive portion of the contact structures. Illustratively, an electrically conductive material may be deposited and pattern to form an electrically conductive layer on the deformable portions 202 of the contact structures 210, and to form electrical wiring on the substrate 206 or substrate portion 208.

[0047] The use of a contact structure and test probe configured as proposed for carrying out an electrical testing of a device will be now described in further detail in relation to FIG.3, which shows a schematic flow diagram of a method 300 of carrying out electrical testing of an electronic device, and FIG.4, which shows a testing system 400 for carrying out an electrical testing of an electronic device. It is understood that the aspects discussed in relation to the testing system 400 may apply to the method 300, and vice versa.

[0048] The method 300 may include, in 310, providing a test probe including one or more deformable contact structures having an electrically conductive portion (e.g., the test probe 200, 420 including deformable contact structures 100, 210, 410 with electrically conductive portion 104, 204, 404).

[0049] The method 300 may further include, in 320, bringing the test probe and the electronic device in contact with one another. Illustratively, the method 300 may include, in 320, bringing the deformable contact structures and electrical contacts of the electronic device in contact with one another to cause a deformation of the deformable contact structures such that the respectiveelectrically conductive portion at least partially conforms to a shape of the corresponding electrical contact. The method 300 may thus include bringing and maintaining the deformable contact structures in contact with the electrical contacts exerting sufficient force to cause a deformation of the deformable portion of the contact structures thereby allowing the electrically conductive portion to conform to the corresponding electrical contact.

[0050] For example, the method 300 may include pushing or compressing the deformable contact structures against the electrical contacts of the device under test to cause a variation of the shape of the contact structures and provide a conformal adaptation of the shape of the electrically conductive portion to the corresponding electrical contact. As will be described in relation to the testing system 400, there may be various ways of bringing the test probe in contact with the device under test, and for holding the deformable contact structures in contact with the electrical contacts. As an example, the method 300 may include establishing a vacuum suction between the test probe and the device under test. As another example, the method 300 may include tightening a fastening element (e.g., a clamp, a screw) to press the deformable contact structures against the electrical contacts.

[0051] In some aspects, the method 300 may further include carrying out an alignment of the deformable contact structures with the electrical contacts before bringing them into contact with one another. For example, the alignment may be an optical alignment, e.g. based on alignment marks present on the test probe and the electronic device under test. As another example, the alignment may be a mechanical alignment based on stopper elements present on holders on which the test probe and the electronic device may be disposed.

[0052] The method 300 may further include, in 330, causing a flow of electrical current into the electronic device through the test probe, e.g. a flow of electrical current into the electrical contacts through the deformable contact structures (maintained in contact with the electrical contacts) to perform an electrical testing of the electronic device. Illustratively, the method 300 may include determining one or more properties of the electronic device based on a response of the device to the flow of electrical current.

[0053] Illustratively, the method 300 may include carrying out an electrical testing of the electronic device by using the test probe to provide temporary electrical contacts for delivering current to the electronic device. As will be described in further detail in relation to the testing system 400, the electrical testing may be carried out in any suitable manner, e.g. depending on which property or parameter of the electronic device should be tested.

[0054] Considering the electrical testing, the method 300 may include determining one or more adjusted parameters associated with the electronic device. For example, the method 300 mayinclude determining one or more adjusted parameters for a fabrication of the electronic device, e.g. to correct defects identified via the electrical testing. The adjusted fabrication parameters may include any suitable parameter that allows for an adaptation of the properties of the electronic device, for example, a deposition time, a thickness of electrically conductive layers, an arrangement of electrical contacts, and the like. As other examples, the method 300 may include determining one or more adjusted parameters for an operation of the electronic device. The adjusted operation parameters may include, as examples, an operating current or operating voltage of the electronic device, an operating temperature, a maximum output power, and the like.

[0055] After the electrical testing has been carried out, the method 300 may include separating the test probe from the electronic device, e.g. removing the deformable contact structures from being in contact with the electrical contacts. In case of elastically deformable contact structures, separating the test probe from the electronic device may cause the deformable contact structures to return to their original (non-deformed) shape. In this scenario, the method 300 may further include carrying out a further electrical testing, e.g. of the same electronic device or another electronic device, re-using the test probe, e.g. by bringing the same test probe into contact with the (same or different) electronic device to cause a conformal contacting of the electrically conductive portions with the electrical contacts of the electronic device.

[0056] In general, electrical testing may be carried out at any suitable stage, e.g. during fabrication or after fabrication of the electronic device. The proposed configuration of the contact structures, however, enables electrical testing also after packaging of the electronic device, illustratively after completion of the module (e.g., after encapsulation in a molding material). In some aspects, the electronic device under test may thus be a packaged electronic device, e.g. a Chip Scale Package (CSP) device. Illustratively, the electronic device may include a packaging encapsulating the electronic components (the integrated circuits) of the device. In this regard, the method 300 may include packaging the electronic device prior to carrying out the electrical testing. For example, the method 300 may be part of a fabrication method of the electronic device, which may include forming the integrated circuit(s) and electrical contact(s) of the electronic device, then packaging the electronic device (e.g., forming an encapsulation, e.g. via molding), and then carrying out the electrical testing as described in relation to the method 300.

[0057] FIG.4 shows a testing system 400 including a test probe 420 and an electronic device under test 430. The testing system 400 may be provided for carrying out an electrical testing of the electronic device 430, e.g. to verify an operation of the electronic device 430 and / or to verifya functioning of electrical contacts and electrical connections of the electronic device 430. The testing system 400 may also be referred to herein as testing arrangement, electrical test system, or circuit probing system. In general, the testing system 400 may be an apparatus configured to carry out the method 300 described in relation to FIG.3

[0058] The test probe 420 may be configured as the test probe 200 described in relation to FIG.2A to FIG.2C and may include one or more contact structures 410 configured as the contact structure 100 described in relation to FIG.1A to FIG. ID. In some aspects, the test probe 420 may include a plurality of contact structures 410. The contact structures 410 may include a deformable portion 402 and an electrically conductive portion 404, as discussed above. For the purpose of illustrating the principles of the testing system 400, the test probe 420 is shown including a substrate 406 on which the one or more contact structures 410 are disposed, e.g. a PCB substrate. It is however understood that the aspects discussed in relation to FIG.3 apply in a corresponding manner to the other configurations discussed in relation to FIG.2A to FIG.2C. It is also understood that the aspects discussed in relation to FIG.4 apply in a corresponding manner to any suitable configuration of the contact structure(s) 410, as discussed in relation to FIG.1 A to FIG. ID.

[0059] The electronic device under test 430 may be any suitable device including electronic components, e.g. any suitable device including one or more integrated circuits. As an example, the electronic device 430 may be an optoelectronic device, for example a light emitting device or a light sensing device. In this configuration, the electronic device 430 may include for example one or more light sources, e.g. one or more laser sources such as one or more VCSELs (Vertical Cavity Surface Emitting Lasers), e.g. a VCSEL array. As another example, the electronic device 430 may include one or more light sensitive elements, e.g. one or more photodiodes, for example configured according to CMOS technology or CCD (Charge-Coupled Device) technology. It is however understood that the electronic device 430 may be any suitable type of device for which electrical testing may be desired, e.g. prior to shipping the electronic device 430 to a client. An electronic device under test (e.g., the electronic device under test 430) may also be referred to herein as electronic device to be tested, device under test, device to be tested, or simply as electronic device.

[0060] The electronic device 430 may include one or more electrical contacts 432 via which electrical signals (e.g., a current) may be provided to the electronic device 430. In general, electrical testing may be carried out at any suitable location, e.g. any suitable electrical contact, of a device to be tested 430. In a preferred configuration, the electrical contacts 432 may be disposed at a backside of the device to be tested 430. For example, the electrical contacts 432may be a backside metallization or may be structured in backside metallization. In an exemplary configuration, the electrical contacts 432 may be a ball grid array. In principle, the electrical contacts 432 may have any suitable shape and any suitable dimension. For example, as shown in FIG.4, the electrical contacts 432 may be contact bumps or contact balls. An “electrical contact” of a device under test may be any suitable location of the electronic device to which an electrical signal (e.g., a current or a voltage) may be supplied. An “electrical contact” of a device under test may be a contact pad, a contact terminal, a contact location, and the like.

[0061] As mentioned in relation to the method 300, in some aspects, the electronic device 430 may be a packaged electronic device, e.g. a CSP optoelectronic device such as a CSP light emitting device or a CSP light sensing device.

[0062] According to various aspects, the testing system 400 may include a positioning system 440 configured to maintain the test probe 420 and the device under test 430 in electrical contact with one another. Illustratively, the positioning system 440 may be configured to maintain the deformable contact structures 410 and electrical contacts 432 of the device in direct contact with one another. The positioning system 440 may be configured to exert a force to maintain the deformable contact structures 410 in contact with the electrical contacts 432 to cause a deformation of the deformable contact structures 410, e.g. to cause a deformation of the deformable portions 402, and to cause the respective electrically conductive portion 404 to at least partially conform to the shape of the corresponding electrical contact 432.

[0063] The positioning system 440 may thus hold a deformable contact structure 410 in contact with a corresponding electrical contact 432 for the duration of the electrical testing, and the compression force to maintain the deformable contact structure 410 in position may cause a deformation of the deformable portion 402 and a corresponding variation of the shape of the electrically conductive portion 404 to adapt to the shape of the electrical contact 432.

[0064] The positioning system 440 may have any suitable configuration to maintain the test probe 420 in contact with the device under test 430. For example, the positioning system 440 may include one or more mechanical components to hold the test probe 420 in contact with the device under test 430, e.g. one or more clamps, one or more screws, and the like. As another example, the positioning system 440 may be a vacuum-based system configured to hold the test probe 420 in contact with the device under test 430 by generating a vacuum suction.

[0065] In some aspects, the positioning system 440 may further be configured to bring the test probe 420 and the device under test 430 into contact with one another. For example, the positioning system 440 may include one or more moving portions, e.g. one or more moving holders on which the test probe 420 and / or the device under test 430 may be disposed.

[0066] For example, the device under test 430 may be disposed (e.g., mounted) on a fixed substrate, and the test probe 420 may be disposed (mounted) on a moving holder movable towards the substrate to bring the deformable contact structure(s) 410 in contact with the electrical contact(s) 432 of the device 330, or vice versa. A “moving portion” may be for example a holder mounted on an automated positioning system.

[0067] In some aspects, the testing system 400 may further include an alignment system configured to align the deformable contact structures 410 with the electrical contacts 432. For example, the alignment system may be an optical alignment system configured to identify a relative disposition of the test probe 420 and device under test 430 via optical inspection, such that the deformable contact structures 410 may be brought into contact with the electrical contacts 432. As another example, the alignment system may be a mechanical alignment system configured to identify a relative disposition of the test probe 420 and device under test 430 based on mechanical features, e.g. stoppers.

[0068] The positioning system 440 may thus in general be configured to hold (and in some aspects also bring) the test probe 420 and the device under test 430 such that the deformable contact structure(s) 410 touch the electrical contact(s) 432, and such that the deformable contact structure(s) 410 undergo a deformation to conform to the shape of the electrical contact(s) 432. The positioning system 440 may thus exert a sufficient holding force thereby causing a deformation of the deformable portion(s) 402 of the contact structure(s) 410 and a corresponding deformation of the electrically conductive portion(s) 404 to allow the electrically conductive portion(s) 404 to conformally adapt to the corresponding electrical contact 432. In some aspects, the positioning system 440 may also be referred to as holder system.

[0069] It is understood that, in principle, it is not required to have a one-to-one relationship between contact structures 410 and electrical contacts 432. In an exemplary configuration, a contact structure 410 may electrically contact a plurality of electrical contacts 432, and may deform to conform to the shapes of the electrical contacts 432 with which the contact structure 410 is in contact. As another exemplary configuration, a plurality of contact structures may electrically contact the same electrical contact 432, and may each deform to conform to the shape of the electrical contact 432 (illustratively, to the shape of the respective contacted portion).

[0070] Each contact structure 410 may thus undergo a respective deformation to conform to the shape of the corresponding electrical contact 432 (or contacts). By using to the proposed strategy, manufacturing tolerances and slight variations in the electrical contacts 432, e.g. in terms of geometry, dimensions, shape, etc., may be “cancelled out” by having contact structures410 that may flexibly adapt to the actual configuration of the electrical contacts 432. Illustratively, a first contact structure 410 may undergo a first deformation to conform to a first electrical contact 432, a second contact structure 410 may undergo a second deformation to conform to a second electrical contact 432, etc. so that a reliable and robust contacting may be ensured for each of the contacts 432 of the device to be tested 430.

[0071] According to various aspects, the testing system 400 may further include a control circuit 450 configured to carry out the electrical testing of the electronic device 430. The control circuit 450 may be configured to cause a flow of electrical current to the electronic device 430 via the test probe 420. Illustratively, the control circuit 450 may be configured to cause a flow of electrical current to the electrical contacts 432 via the corresponding contact structures 410 (being in contact with the electrical contacts 432), e.g. via the electrically conductive portion 404 of the corresponding contact structures 410. The control circuit 450 may thus perform an electrical testing of the electronic device 430 based on a response of the electronic device 430 to the received electrical current. In this regard, the control circuit 450 may include or may control one or more electrical sources, e.g. one or more current sources and / or voltage sources, to deliver current to the test probe 420. For example, the one or more current sources and / or voltage sources may be coupled with the electrical wiring of the test probe 420 to deliver current to the electrically conductive portions 404 of the contact structures 410.

[0072] In principle, any suitable electrical property or function of the electronic device 430 may be tested. In a simple configuration, the control circuit 450 may deliver current to the electronic device 430 via the test probe 420 to verify whether the electronic device 430 may turn on and off according to an intended operation. For example, in case of a light emitting device, the control circuit 450 may deliver current to verify whether the electronic device 430 emits light at a predefined intensity, or with a predefined pattern, etc. As another example, in case of a light sensing device, the control circuit 450 may deliver current to verify whether the electronic device 430 may sense light.

[0073] In a more complex configuration, the control circuit 450 may deliver current to the electronic device 430 via a predefined pattern. For example, at a first time point the control circuit 450 may deliver current to a first subset of the contact structures 410, at a second time point the control circuit 450 may deliver current to a second subset of the contact structures 410, etc. This type of testing may allow evaluating the behavior of different parts of the electronic device 430, for example to fire up different light sources (e.g., different VCSELs), to activate different sensor pixels (different photodiodes), and the like. For example, the control circuit 450 may deliver current to the contact structures 410 in sequence, e.g. starting from aninitial position of the array of contact structures 410 and proceeding sequentially up to a final position of the array.

[0074] After the electrical testing has been performed, the positioning system 440 may separate the test probe 420 from the electronic device 430. For example, the control circuit 450 may send a control signal to the positioning system 440 indicating the completion of the electrical testing, thus triggering the separation of the test probe 420 from the electronic device 430.

[0075] As mentioned above, the deformable contact structures proposed herein may have any suitable shape, which may be adapted depending on the configuration of the electrical contacts of the device to be tested. In this regard, FIG.5A to FIG.5G show possible configurations and shapes of deformable contact structures in a schematic representation, according to various aspects. The shapes described in relation to FIG.5 A to FIG.5G have been found to enable a suitable implementation of the proposed approach. It is however understood that a contact structure may also have any suitable shape other than those shown.

[0076] In FIG.5A to FIG.5G, configurations of contact structures 500a-500g, 550a-550g are shown in which the respective deformable portions 502a-502g are formed monolithically with a substrate portion 508a-508g, or are disposed on a carrier substrate 506a-506b, or are both monolithically formed and disposed on a (rigid) substrate. It is understood that the aspects described in relation to a certain configuration apply in a corresponding manner to any of the possible configurations.

[0077] As an exemplary configuration 500a, 550a, as shown in FIG.5A, a contact structure 510a may have a planar shape. In this scenario, the deformable portion 502a may be a sheet of deformable material, e.g. a sheet of elastomer material. The electrically conductive portion 504a may be disposed on the sheet of deformable material or part of the sheet of deformable material, as discussed above. In this configuration, the electrically conductive portion 504a may thus have a planar shape (when non-deformed). For example, the deformable portion 502a may be understood as the part of substrate portion 508a disposed in correspondence of the electrically conductive portion 504a, e.g. disposed underneath the electrically conductive portion 504a. This configuration may allow a simpler fabrication process, without a structuring to define the deformable portion 502a.

[0078] As another exemplary configuration 500b, 550b, as shown in FIG.5B, a contact structure 510b may have a dome shape, e.g. a contact structure 510b may have the deformable portion 502b having a dome shape on the substrate 506b or substrate portion 508b. As mentioned, this shape may facilitate the contacting with the electrical contacts of a device to be tested. In an exemplary configuration, the electrically conductive portion 504b may conform to the domeshape of the deformable portion 502b, e.g. the electrically conductive portion 504b may be disposed to cover the dome-shaped deformable portion 502b.

[0079] As a further exemplary configuration 500c, 550c, as shown in FIG.5C, a contact structure 510c may include alternating hills and valleys, e.g. a contact structure 510c may include one or more hill portions and one or more valley portions. For example, in the configuration in FIG.5C the contact structure 510c may include two hill portions (e.g., two dome-shaped portions) with a valley portion therebetween. In other configurations, a contact structure 510c may include two valley portions with a hill portion therebetween, or more than two hill portions and / or valley portions. Illustratively, as shown in FIG.5C the contact structure 510c may include portions with different height, e.g. one or more (hill) portions disposed on or extending above the main surface of the substrate 506c or substrate portion 508c, and one or more (valley) portions disposed extending below the level of the main surface of the substrate 506c or substrate portion 508c. The hills and valleys may be coupled by structuring the electrically conductive portion 504c.

[0080] As another exemplary configuration 500d, 550d, as shown in FIG.5D, a contact structure 5 lOd may have a pyramid shape or cone shape, e.g. a contact structure 5 lOd may have the deformable portion 502d having a pyramid / cone shape on the substrate 506d or substrate portion 508d. A pointy shape as a pyramid or cone may be provided, for example, in case the device to be tested has a narrow access to the electrical contacts, e.g. narrow openings through which the contact structure 510d should pass.

[0081] As shown in the configuration 500e, 550e in FIG.5E also a “reverse” configuration may be provided, in which a contact structure 510e may have a substrate portion 508e structured to define a cavity into which the electrically conductive portion 504e is disposed. For example, as shown in FIG.5E, the contact structure 510e may have an inverse pyramid shape or inverse cone shape, but also other shapes may be provided for the cavity. In this scenario the deformable portion 502e may be understood as the part of substrate portion 508e disposed in correspondence of the electrically conductive portion 504e. This configuration may be provided, for example, for “mating” with corresponding electrical contacts of the device to be tested.

[0082] According to various aspects, as shown for the configuration 500f, 500g, 550f, 550g in FIG.5F and FIG.5G, a contact structure 5 lOf, 510g may include a plurality of portions each configured to be deformable by a respective deformation force. For example, a contact structure 51 Of, 510g may include a first portion configured to be deformable by a first deformation force and a second portion configured to be deformable by a second deformation force different fromthe first deformation force. For example, the contact structure 5 lOf, 510g may be shaped to obtain different stiffness in different portions of the contact structure 51 Of, 510g. As an example, the first portion may be deformable with less force compared to the second portion, so that when the contact structure 51 Of, 510g is brought into contact with an electrical contact the first portion may undergo a deformation while the second portion may remain non-deformed and act as a “stop” for the placement of the contact structure 51 Of, 510g.

[0083] There may be various ways to obtain a contact structure 51 Of, 510g having portions (or regions) with different deformability. As an example, as shown in FIG.5F and FIG.5G, a contact structure 5 lOf, 510g may have a step-like shape, e.g. the deformable portion 502f, 502g may have a staircase shape in which each “step” or “stair” correspond to a region with different deformability. In this configuration, a contact structure 51 Of, 510g may thus define a profile for the force required to cause a deformation of the contact structure 51 Of, 510g.

[0084] According to various aspects, as shown in FIG.6A to FIG.6C, the deformable portion of a contact structure may include different materials with different stiffness, to tailor the properties of the contact structure. A contact structure 600 may thus include a deformable portion divided into a plurality of regions each including or being made of a different material. For example, the materials may be disposed in order of stiffness, e.g. with greater stiffness towards the inside and a softer layer at the outside to be easily deformed, or vice versa with a flexible core that allows deforming the larger structure and then another material that may be more easily coated with an electrically conductive layer.

[0085] In various aspects, a contact structure 600 may include a deformable portion 602 with a plurality of regions. For example, as shown in FIG.6A, the deformable portion 602 may include a first region 602a, e.g. an inner region, and a second region 602b, e.g. an outer region. It is however understood that the aspects discussed in relation to FIG.6A may extend to any suitable number of regions, e.g. a third region, a fourth region, etc. Illustratively, the first region 602a may be a “core” or “bulk” region of the deformable portion 602, and may be surrounded by the second region 602b (illustratively, an outer shell). The second (outer) region 602b may be closer to the electrically conductive portion 604 compared to the first (inner) region 602a. For example, the electrically conductive portion 604 may be an electrically conductive layer disposed on the outer region 602b.

[0086] As mentioned, the different regions of the deformable portion 602 may include different materials. In the exemplary configuration of FIG.6A, the first region 602a may include or may be made of a first material and the second region 602b may include or may be made of a second material, different from the first material (e.g., with a different stiffness). A third region mayinclude or may be made of a third material different from the first material and second material, etc. The stiffness profile of the deformable contact structure 600 may be engineered according to a desired configuration. As an example, the first material may have a greater stiffness compared to the second material, e.g. the stiffness profile may go from a high stiffness at the core to a low stiffness at the outside. As another example, the first material may have a lower stiffness compared to the second material, e.g. the stiffness profile may go from a low stiffness at the core to a high stiffness at the outside.

[0087] As shown in FIG.6B, the configuration with multiple materials may be provided in case the contact structures 600 are disposed on a substrate 606b (configuration 650b), and / or in case the deformable portion 602 is monolithically formed with a substrate portion 608b (configuration 600b). In this second case, the substrate portion 608b may be made of the same material as the most inner region of the deformable portion, e.g. the material of the first region 602a in the configuration in FIG.6B.

[0088] As shown in FIG.6B, the configuration with multiple materials may be provided in case a contact structure 600 has a planar configuration, e.g. disposed on a substrate 606c (configuration 650c), and / or monolithically formed with a substrate portion 608c (configuration 600c). In this scenario, a region 602a with different material may be formed in a cavity of the substrate portion 608c. Illustratively, the first (inner) region 602a may be a cavity filled with the first material, and surrounded by the second (outer) region 602b of second material. For example, the second (outer) region 602b may be understood as the part of substrate portion 608c in correspondence of the electrically conductive portion 604 (e.g., underneath the electrically conductive portion 604).

[0089] According to various aspects, as shown in FIG.7A to FIG.7D, a contact structure or a test probe may further include one or more channels extending therethrough, to provide further functionalities exploitable for carrying out the electrical testing.

[0090] As shown in FIG.7A and FIG.7B, a contact structure 700a, 700b may include a channel 710a, 710b extending through the contact structure 700a, 700b. The channel 710a, 710b may be an open channel extending through the deformable portion 702a, 702b and electrically conductive portion 704a, 704b. The channel 710a, 710b may further extend through the substrate 706a, 706b and / or substrate portion (not shown in FIG.7A and FIG.7B). Although in FIG.7A and FIG.7B a single channel 710a, 710b is illustrated, in some aspects a contact structure 700a, 700b may include a plurality of channels 710a, 710b extending therethrough. The channel 710a, 710b may thus be understood as a hollow portion of the deformable portion 702a, 702b (and substrate 706a, 706b, and / or substrate portion).

[0091] As shown in combination with an electrical contact 720a, 720b of an electronic device, the channel(s) 710a, 710b may be used to enhance the contacting between the contact structure 700a, 700b and the electrical contact 720a, 720b. For example, the channel(s) 710a, 710b may be vacuum channels used to establish a vacuum between the contact structure 700a, 700b and the electrical contact 720a, 720b, e.g. via suction from the channel(s) 710a, 710b. The contact structure 700a, 700b may thus be brought into contact with the electrical contact 720a, 720b by establishing a vacuum between the deformable contact structure 700a, 700b and the electrical contact 720a, 720b through the channel(s) 710a, 710b (e.g., as part of the method 300, e.g. as functionality of the positioning system 440).

[0092] As an exemplary configuration, as shown in FIG.7A and FIG.7B, in the presence of a channel 710a, 710b the electrically conductive portion 704a, 704b may be formed along the sidewall of the channel 710a, 710b, e.g. as a layer formed on the sidewall of the channel 710a, 710b. As mentioned above, the electrically conductive portion 704a, 704b may be structured to provide an electrical wiring 712a, 712b (e.g., to couple the contact structure 700a, 700b with a current source or voltage source). For example, the electrical wiring 712a, 712b may be formed in the part of the channel 710a, 710b in the substrate 706a, 706b of the contact structure 700a, 700b.

[0093] The aspects discussed in relation to FIG.7A to FIG.7B may be extended to a test probe 750c, 75 Od with a plurality of contact structures 700c, 700d, as shown in FIG.7C and FIG.7D. In the configuration in FIG.7C and FIG.7D the test probe 750c, 750d may include a plurality of (vacuum) channels 710c, 710d extending through the substrate 706c, 706d (and substrate portion 708d), but not through the deformable portion 702c, 702d and electrically conductive portion 704c, 704d of the contact structures 700c, 700d. It is however understood that the aspects discussed in relation to FIG.7C and FIG.7D may apply in a corresponding manner to a configuration in which channels extend through the deformable portion 702c, 702d and electrically conductive portion 704c, 704d of the contact structures 700c, 700d, e.g. in addition or in alternative to the channels 710c, 71 Od extending through the substrate 706c, 706d.

[0094] For example, a channel 710c, 710d may be disposed between adjacent contact structures 700c, 700d. As an exemplary testing scenario, the electrical contacting may be obtained by placing a channel 710c, 710d in correspondence of a corresponding electrical contact 720c of the device under test. In this scenario, as shown in FIG.7C and FIG.7D, the electrical contact 720c may be brought into contact with two adjacent contact structures 700c, 700d, e.g. by establishing a vacuum through the channel 710c, 710d. The vacuum channels ensure thus a stable holding of the contact structures 700c, 700d against the electrical contacts 720c, 720d.

[0095] According to various aspects, as shown in FIG.7D a test probe 750d may further include a sealing structure 714d configured to enhance the establishing of a vacuum for holding the test probe 750d in contact with the device under test. The sealing structure 714d may be for example a sealing ring, e.g. disposed around the contact structures 700d, for example disposed along the perimeter of an array of contact structures 700d. The sealing structure 714d provide sealing off pressure during the contacting. As an exemplary configuration, the sealing structure 714d may be provided by structuring the substrate portion 708d of the contact structures 700d (e.g., the sealing structure 714d may be monolithically formed with the substrate portion 708d), or may be a separate element disposed on the substrate 706d or substrate portion 708d of the test probe 750d. The integration of additional features, e.g. sealing structures, in the substrate portion (e.g., in the elastic substrate) allows for a time- and resource-efficient fabrication of the test probe.

[0096] The term “control circuit” (or processing circuit) as used herein may be understood as any kind of technological entity that allows handling of data. The data may be handled according to one or more specific functions that the control circuit may execute. Further, a control circuit as used herein may be understood as any kind of circuit, e.g., any kind of analog or digital circuit. A control circuit may thus be or include an analog circuit, digital circuit, mixed-signal circuit, logic circuit (e.g., a hard-wired logic circuit or a programmable logic circuit), microprocessor, Central Processing Unit (CPU), Graphics Processing Unit (GPU), Digital Signal Processor (DSP), Field Programmable Gate Array (FPGA), integrated circuit, Application Specific Integrated Circuit (ASIC), etc., or any combination thereof.

[0097] The word “exemplary” is used herein to mean “serving as an example, instance, or illustration”. Any embodiment or design described herein as “exemplary” is not necessarily to be construed as preferred or advantageous over other embodiments or designs.

[0098] The phrase “at least one” and “one or more” may be understood to include a numerical quantity greater than or equal to one (e.g., one, two, three, four, [...], etc.). The phrase “at least one of’ with regard to a group of elements may be used herein to mean at least one element from the group consisting of the elements. For example, the phrase “at least one of’ with regard to a group of elements may be used herein to mean a selection of: one of the listed elements, a plurality of one of the listed elements, a plurality of individual listed elements, or a plurality of a multiple of individual listed elements.

[0099] All acronyms defined in the above description additionally hold in all claims included herein.

[0100] While the invention has been particularly shown and described with reference to specific aspects, it should be understood by those skilled in the art that various changes in formand detail may be made therein without departing from the spirit and scope of the invention as defined by the appended claims. The scope of the invention is thus indicated by the appended claims and all changes, which come within the meaning and range of equivalency of the claims, are therefore intended to be embraced.List of reference signs100 Contact structure 440 Positioning system 100a Contact structure 450 Control circuit 100b Contact structure 500a First configuration 100c Contact structure 500b Second configuration lOOd Contact structure 500c Third configuration 102 Deformable portion 500d Fourth configuration 104 Electrically conductive portion 500e Fifth configuration 106 Substrate 500f Sixth configuration 108 Substrate portion 500g Seventh configuration 110 Lateral extension 502a Deformable portion 112 Height 502b Deformable portion 200 Test probe 502c Deformable portion 200a Test probe 502d Deformable portion 200b Test probe 502e Deformable portion 200c Test probe 502f Deformable portion 202 Deformable portion 502g Deformable portion 204 Electrically conductive portion 504a Electrically conductive portion 206 Substrate 504b Electrically conductive portion 208 Substrate portion 504c Electrically conductive portion 210 Contact structure 504d Electrically conductive portion 300 Method 504e Electrically conductive portion 310 Method step 504f Electrically conductive portion 320 Method step 504g Electrically conductive portion 330 Method step 506a Substrate 400 Testing system 506b Substrate 402 Deformable portion 506c Substrate 404 Electrically conductive portion 506d Substrate 406 Substrate 506e Substrate 410 Contact structure 506f Substrate 420 Test probe 506g Substrate 430 Electronic device 508a Substrate portion 432 Electrical contact 508b Substrate portion8c Substrate portion 700a Contact structure8d Substrate portion 700b Contact structure 8e Substrate portion 700c Contact structure 8f Substrate portion 700d Contact structure 8g Substrate portion 702a Deformable portion 0a Contact structure 702b Deformable portion 0b Contact structure 702c Deformable portion 0c Contact structure 702d Deformable portion Od Contact structure 704a Electrically conductive portion Oe Contact structure 704b Electrically conductive portion Of Contact structure 704c Electrically conductive portion0g Contact structure 704d Electrically conductive portion0a First configuration 706a Substrate 0b Second configuration 706b Substrate 0c Third configuration 706c Substrate 0d Fourth configuration 706d Substrate 0e Fifth configuration 708d Substrate portion 0f Sixth configuration 710a Channel 0g Seventh configuration 710b Channel 0 Contact structure 710c Channel 0b First configuration 710d Channel 0c First configuration 712a Electrical wiring 2 Deformable portion 712b Electrical wiring 2a Inner region 712c Electrical wiring 2b Outer region 712d Electrical wiring 4 Electrically conductive portion 714d Sealing structure 6b Substrate 720a Electrical contact 6c Substrate 720b Electrical contact 8b Substrate portion 720c Electrical contact 8c Substrate portion 720d Electrical contact 0b Second configuration 750c Test probe 0c Second configuration 750d Test probe

Claims

Claims1. A method (300) of electrically testing an electronic device, the method (300) comprising: providing (310) a test probe, wherein the test probe comprises a deformable contact structure with an electrically conductive portion; bringing (320) the deformable contact structure and an electrical contact of the electronic device into contact with one another to cause a deformation of the deformable contact structure such that the electrically conductive portion at least partially conforms to a shape of the electrical contact of the electronic device; and causing (330) a flow of electrical current into the electrical contact of the electronic device through the electrically conductive portion of the deformable contact structure to perform an electrical testing of the electronic device.

2. The method (300) according to claim 1, wherein the deformable contact structure has a first shape when the deformable contact structure is not in contact with the electrical contact of the device; and wherein the deformable contact structure assumes a second shape when the deformable contact structure is in contact with the electrical contact of the device to conform to the shape of the electrical contact.

3. The method (300) according to claim 2, further comprising: separating the deformable contact structure from the electrical contact of the electronic device, wherein the deformable contact structure returns to the first shape when the deformable contact structure is separated from the electrical contact.

4. The method (300) according to claim any one of claims 1 to 3,wherein the deformable contact structure is elastically deformable, and wherein the deformation of the deformable contact structure caused by bringing the deformable contact structure and the electrical contact of the electronic device into contact with one another is an elastic deformation of the deformable contact structure.

5. The method (300) according to claim any one of claims 1 to 4, wherein the deformable contact structure comprises or is made of an elastomer material.

6. The method (300) according to claim any one of claims 1 to 5, wherein the deformable contact structure has a lateral extension in a main surface of the test probe in the range from 100 nm to 500 pm and / or a height in a direction perpendicular to the main surface of the test probe in the range from 100 nm to 500 pm.

7. The method (300) according to claim any one of claims 1 to 6, wherein the deformable contact structure comprises a deformable portion comprising: an inner region comprising or made of a first material, and an outer region comprising or made of a second material having a different stiffness compared to the first material.

8. The method (300) according to claim any one of claims 1 to 7, wherein the deformable contact structure comprises a first portion deformable with a first deformation force, and a second portion deformable with a second deformation force different from the first deformation force, and wherein the deformation of the deformable contact structure caused by bringing the deformable contact structure and the electrical contact of the electronic device intocontact with one another comprises a deformation of the first portion without causing a deformation of the second portion.

9. The method (300) according to claim any one of claims 1 to 8, wherein the deformable contact structure comprises at least one channel extending through the deformable contact structure; and wherein bringing the deformable contact structure and the electrical contact of the electronic device into contact with one another comprises establishing a vacuum between the deformable contact structure and the electrical contact through the at least one channel.

10. The method (300) according to claim any one of claims 1 to 9, further comprising: packaging the electronic device prior to bringing the deformable contact structure and the electrical contact of the electronic device into contact with one another.

11. A testing system (400) for electrically testing an electronic device, the testing system (400) comprising: a test probe (420) comprising a deformable contact structure (410) with an electrically conductive portion (404); a positioning system (440) configured to maintain the deformable contact structure (410) and an electrical contact (432) of an electronic device (430) in contact with one another to cause a deformation of the deformable contact structure (410) such that the electrically conductive portion (404) at least partially conforms to a shape of the electrical contact (432) of the electronic device (430).

12. The testing system (400) according to claim 11, further comprising: a control circuit (450) configured to cause a flow of electrical current into the electrical contact (432) of the electronic device (430) through the electrically conductiveportion (404) of the deformable contact structure (410) to perform an electrical testing of the electronic device (430).

13. The testing system (400) according to claim 11 or 12, further comprising: the electronic device (430).

14. The testing system (400) according to any one of claims 11 to 13, wherein the deformable contact structure (410) comprises or is made of an elastomer material.

15. A contact structure (100) for a test probe for carrying out an electrical testing of an electronic device, the contact structure (100) comprising: a deformable portion (102) configured to be elastically deformable; and an electrically conductive portion (104), wherein the deformable portion (102) is configured to deform when the contact structure (100) is brought into contact with an electrical contact of the electronic device to cause the electrically conductive portion (104) to at least partially conform to a shape of the electrical contact.

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