MEASURING PROBE FOR TESTING SEMICONDUCTOR DEVICES ON A WAVELENGTH, AND ITS MANUFACTURING PROCESS

Abstract

The invention relates to a measuring probe for testing wafer-based semiconductor devices, comprising: - a central conductive wire extending from the connection end to the probing end; - a dielectric sheath covering the central conductive wire, the dielectric sheath being tapered at a portion, called the probing portion, of the measuring probe, the probing portion being substantially straight or curved and terminating at the probing end; - a main conductive layer covering at least the dielectric sheath and partially covering at least one facet (16); the measuring probe further comprises a central tip (18) and at least one lateral tip (19) located on at least one facet (16), the central tip (18) and at least the lateral tip (19) being designed to make contact with contact pads on the wafer. Figure 3

Description

Title of the invention: Measuring probe for testing semiconductor devices on a wafer, and its manufacturing process. FIELD OF THE INVENTION

[0001] The present invention relates to the field of wafer-based device testing. In particular, the present invention relates to a measuring probe for testing semiconductor devices formed on a wafer. DESCRIPTION OF RELATED ART

[0002] US6078184 discloses a measuring probe for contacting microwave circuits planar and comprises a substrate with a coplanar line in a housing in which a coaxial line terminal is constructed and from which at least two contact fingers extend. One end of the coplanar line is connected to the coaxial line terminal and the other end is connected to the contact fingers. The contact fingers consist of thin spring steel needles arranged side by side.

[0003] Other forms of measuring probes are also disclosed in documents US20030132759, US20020163349 and US6118287.

[0004] Such a measuring probe covers the distance between a proximal end for mechanical attachment and a standardized electrical contact of the probe, and a distal end configured to make contact with contact pads on a silicon wafer. The distal end comprises a plurality of contacts, for example, to contact the ground-signal-ground pads of an RF circuit to be tested on the silicon wafer.

[0005] The size and spacing of the contacts must correspond to the size and spacing (pitch) of the contact pads of the device under test. For manufacturing reasons, in known measuring probes, the size of the contact fingers is greater than 25 microns and their spacing is between 25 and 100 microns.

[0006] To accommodate the decreasing size of semiconductor devices and to improve RF performance (less capacitive effect), it would generally be advantageous to have measuring probes with contact fingers whose size and spacing are reduced compared to the size and spacing of the prior art. In this regard, patent application WO 2021 / 069566 discloses a coaxial wafer probe. In particular, this coaxial probe includes contact fingers at a distal end for making contact with the contact pads of a wafer.

[0007] However, the contact fingers are fragile and do not ensure optimal electrical contact with the contact pads, particularly in applications where the oxide layers passivating these pads must be broken.

[0008] In addition, the reduction of the contact finger pitch is very limited due to the necessary cut between the fingers.

[0009] The present invention aims to solve, at least partially, these problems and to improve the RF and microwave separation of the probe. Summary of the invention

[0010] The aforementioned objectives of the present invention are, at least partially, achieved by a measuring probe for testing wafer-based semiconductor devices, extending from a connection end to a probing end, the probing end forming at least one facet, the measuring probe comprising:

[0011] - a central conducting wire extending from the connection end to the end of survey ;

[0012] - a dielectric sheath covering the central conductor wire, the dielectric sheath being tapered at the level of a portion, called the sounding portion, of the measuring probe, the sounding portion being substantially straight or curved and ending with the sounding end;

[0013] - a main conductive layer covering at least the dielectric sheath and at least one facet partially;

[0014] the measuring probe further comprises a central tip and at least one lateral tip located on at least one facet, the central tip and at least one lateral tip being designed to make contact with contact pads on the wafer.

[0015] According to one embodiment, the height H of the central point and of at least one lateral point is less than half of the distance D separating the top of the central point and the top of at least one lateral point.

[0016] According to one embodiment, the central point and at least one lateral point have the shape of a truncated cone or several truncated cones.

[0017] According to one embodiment, the height of the central tip and the height of the lateral tip are between 1 micrometer and 25 micrometers, and / or the distance between the central tip and the lateral tip is between 1 micrometer and 70 micrometers, advantageously between 1 micrometer and 50 micrometers, more advantageously between 1 micrometer and 25 micrometers.

[0018] According to one embodiment, the central tip and the lateral tip comprise a conductive material having a Brinell hardness greater than 100, advantageously, the conductive material comprises tungsten, platinum, tungsten carbide, titanium nitride or nickel.

[0019] According to one embodiment, the dielectric sheath comprises glass and / or the central conducting wire comprises a platinum and iridium alloy, and / or the main conducting layer comprises at least one of the elements selected from: gold, platinum, tungsten.

[0020] According to one embodiment, the central conducting wire has, at the probing end, a diameter less than or equal to 30 micrometers, advantageously less than or equal to 20 micrometers, more advantageously less than or equal to 10 micrometers, even more advantageously less than or equal to 5 micrometers, and even less than 1 micrometer.

[0021] According to one embodiment, at least one facet comprises a main facet and a lateral facet, the main facet being substantially orthogonal to the extension direction of the drilling portion, while the lateral facet forms a bevel of the drilling end, advantageously the main facet is substantially free of any electrically conductive material.

[0022] According to one embodiment, the central point and at least one lateral point are formed on the lateral facet.

[0023] According to one embodiment, the main conductive layer comprises a peripheral section formed on at least one facet, and on which at least one lateral tip is formed.

[0024] According to one embodiment, the measuring probe further comprises an electrically conductive layer, called central zone, formed only on at least one facet, which is electrically isolated from the main conductive layer, and the central zone is in electrical contact with the end of the central conducting wire, the central zone ensuring electrical contact between the central tip and the end of the central conducting wire.

[0025] According to one embodiment, the central zone is interposed between the central point and at least one facet.

[0026] According to one embodiment, the central zone is electrically isolated from the main conductive layer by a non-conductive zone.

[0027] According to one embodiment, a conductive contact layer, comprising an electrically conductive material having a Brinell hardness greater than 100, is formed on the central tip and / or the lateral tip, advantageously the electrically conductive material comprises at least one of the elements selected from: tungsten, titanium nitride, tungsten carbide, nickel or platinum.

[0028] According to one embodiment, the conductive contact layer formed on the central tip is also in electrical contact with the end of the central conducting wire and / or the conductive contact layer formed on the lateral tip is also in electrical contact with the main conducting layer.

[0029] The invention also relates to a method for manufacturing a measuring probe for testing semiconductor devices on the wafer, which consists of

[0030] a) insert a conducting wire into a central hole of a dielectric capillary;

[0031] b) heat and stretch the dielectric capillary over the conducting wire by separating the two ends to form a tapered dielectric sheath on the conductor wire;

[0032] c) separating the conductive wire and the dielectric layer in a separation zone to obtain two separate portions, the tapered dielectric sheath covering a probing portion of a central conductive wire of each separated portion,

[0033] d) form at least one facet at a free end, called the drilling end, of the drilling portion, the formation of at least one facet being carried out in such a way that the end of the conducting wire at the drilling end is flush with the at least one facet;

[0034] e) form a main conductive layer on at least one of the separated portions, the main conductive layer covering the tapered dielectric sheath and partially at least one facet of the considered separated portion;

[0035] g) form a central point and at least one lateral point on at least one facet.

[0036] According to one embodiment, said manufacturing process further comprises a step f) of forming an electrically conductive layer, said central zone, formed only on at least one facet, which is electrically isolated from the main conductive layer and which establishes electrical contact with the end of the central conductive wire.

[0037] According to one embodiment, step e) comprises the formation of an electrically conductive layer on the tapered dielectric sheath and at least one facet, and step f) is partial removal of the electrically conductive layer to form a non-conductive area on at least one facet, advantageously, the removal is carried out by spraying or etching, more advantageously the spraying is carried out by a focused ion beam.

[0038] According to one embodiment, step g) is carried out by an additive method, advantageously the tips are produced with conductive materials such as copper.

[0039] According to one embodiment, step g) is accomplished by removing material, advantageously by a focused ion beam.

[0040] According to one embodiment, said manufacturing process further comprises the execution of a step h), step h) comprises the deposition of a conductive contact layer, comprising an electrically conductive material having a Brinell hardness greater than 100, on the central tip and at least one lateral tip, advantageously the electrically conductive material comprises at least one of the elements chosen from: tungsten, titanium nitride, tungsten carbide, nickel or platinum.

[0041] According to one embodiment, in step e), the main conductive layer is deposited by masking and evaporation. DESCRIPTION OF THE DRAWINGS

[0042] Other features and advantages will be better understood upon reading the following description of the present invention, provided by way of non-limiting examples, with reference to the accompanying drawings, in which:

[0043] [Fig-1] Fig. 1 represents a test system that can contain a probe measurement and a probe holder according to the invention;

[0044] [Fig.2] Fig.2 represents a measuring probe according to the present invention, in In particular, [Fig.2] represents the measuring probe according to a longitudinal cross-section;

[0045] [Fig. 3] Fig. 3 represents the central point and at least one lateral point arranged on a lateral facet;

[0046] [Fig. 4] [Fig. 4] represents the central point and at least one lateral point arranged on a lateral facet;

[0047] [Fig.5a]

[0048] [Fig.5b]

[0049] [Fig.5c]

[0050] [Fig.5d]

[0051] [Fig.5e]

[0052] [Fig.5f]

[0053] [Fig.5g]

[0054] Figures 5a to 5g represent a method of manufacturing a measuring probe according to the invention. DETAILED DESCRIPTION OF THE INVENTION

[0055] In the descriptive part, the same reference numerals in the drawings may be used for elements of the same type. The drawings are schematic representations which, for reasons of legibility, are not necessarily to scale.

[0056] The present invention relates to a measuring probe for testing semiconductor devices on a wafer. In particular, the present invention relates to a measuring probe equipped with contact points arranged at one probing end of the measuring probe.

[0057] The invention relates to a measuring probe, for the on-wafer testing of semiconductor devices, extending from one connecting end to one end of sounding, the sounding end forming at least one facet, the measuring probe comprising:

[0058] - a central conducting wire extending from the connection end to the end of survey ;

[0059] - a dielectric sheath covering the central conductor wire, the dielectric sheath being tapered at the level of a portion, called the sounding portion, of the measuring probe, the sounding portion being substantially straight or curved and ending with the sounding end;

[0060] - a main conductive layer covering at least the dielectric sheath and at least one facet partially;

[0061] the measuring probe further comprises a central tip and at least one lateral tip located on at least one facet, the central tip and the at least lateral tip being designed to make contact with contact pads on the plate.

[0062] It is understood that the main conductive layer, the dielectric sheath and the central conductive wire are configured to transmit the signal (for example the radio frequency signal) to the lateral end and the central end, respectively.

[0063] The invention relates to a measuring probe for testing wafer-based semiconductor devices, extending from a connection end to a probing end, the probing end forming at least one facet, the measuring probe comprising:

[0064] - a central conducting wire extending from the connection end to the end of survey ;

[0065] - a dielectric sheath covering the central conductor wire, the dielectric sheath being tapered at the level of a portion, called the sounding portion, of the measuring probe, the sounding portion being substantially straight and ending with the sounding end;

[0066] - a main conductive layer covering at least the dielectric sheath and at least one facet partially;

[0067] The measuring probe further comprises an electrically conductive layer, said central zone, formed only on at least one facet, which is electrically insulated from the main conductive layer and which covers the end of the central conductive wire, the measuring probe further comprises a central tip and at least one lateral tip disposed on at least one facet, the central tip and at least one lateral tip being designed to make contact with contact pads on the wafer.

[0068] It is understood, without the need to specify it, that the end of the central conducting wire at the probing end, said conducting end, is flush with at least one facet. According to this configuration, the central area covers, at least in part, the conducting end.

[0069] The contact tip manufactured by microfabrication techniques may have a reduced size and a small spacing compared to the fingers considered in the prior art.

[0070] Furthermore, using a central zone electrically isolated from the main conductive layer, instead of fingers for the electrical insulation of the contact points, improves the rigidity of the contact between the contact points and the contact pads. In particular, the electrical insulation of the central zone from the main conductive layer can be achieved by including a non-conductive zone, and specifically a non-conductive zone surrounding the central zone. In this regard, and without limiting the invention to this aspect alone, the non-conductive zone may include a groove.

[0071] Finally, the small size of the contact tip and the implementation of the conductive layer improve the screening of the measuring probes and reduce crosstalk during use.

[0072] Fig. 1 represents a test system 1 that can contain the measuring probe and a probe holder according to the invention.

[0073] In this figure, a plate W is arranged on a movable table 2. The table 2 can be moved in the plane along the x and y directions to position selected contact pads of the plate W near the contact tips of the measuring probes. Typically, the table 2 can be moved with an accuracy on the order of 100 nm to 5 microns.

[0074] In the example of [Fig. 1], the test system 1 is a two-port system and comprises two probe holders 3, 3' fixed to the ends of two movable arms (not shown in [Fig. 1]). Each probe holder 3, 3' can be moved in the x, y, z directions, typically over a distance of approximately 100 microns to several hundred microns with high accuracy from less than one micron up to 10 nm. Each movable arm may include one or more piezoelectric actuators for the highly precise movement of each probe holder 3, 3'.

[0075] Each probe holder 3, 3' is electrically connected, for example by a coaxial cable 5, to at least one test unit such as a vector network analyzer.

[0076] A measuring probe 10 has a connection end 10a that is conductively attached to the probe holder. The probe holder establishes the electrical connection between the measuring probe 10 and the connector 3a, so that the electrical signals measured at a probing end 10b of the measuring probe 10 are effectively transmitted to the test unit via the coaxial cable 5.

[0077] As will be described in more detail in another section of this description, the measuring probe 10 is advantageously provided, at its probing end 10b forming at least one facet 16, with a plurality of contact points, at less to conduct a line signal and a ground (earth) signal to the test unit. Preferably, the measuring probe 10 is provided with three contact points to connect to the ground-signal-ground pads of an RF device under test arranged on the W plate.

[0078] Once the measuring probe 10 is in contact with the contact pads of the wafer W, the test unit can be used to provide and collect signals to / from the device under test in order to efficiently test its operation and performance.

[0079] Fig. 2 is a longitudinal sectional representation of a measuring probe 10 according to the present invention.

[0080] The measuring probe 10 extends from a connection end 10a to a probing end 10b, the probing end 10b forming at least one facet. In particular, the measuring probe may comprise, from the connection end 10a to the probing end 10b, a support portion 14 and a probing portion 13. It is understood that the probing portion 13 and the support portion 14 are both elongated.

[0081] The measuring probe 10 includes a central conductive wire 11, for example made of a platinum-iridium alloy. The central conductive wire 11 extends between the connection end 10a and the probing end 10b to conduct an electrical signal from the contact area of ​​the wafer W to the connector 3a. The end of the central conductive wire 11 is in electrical contact with a contact point, called the central point, formed on the probing end 10b of the measuring probe 10. The central conductive wire 11 may be tapered, that is, have a diameter that generally decreases from the proximal end to the distal end of the measuring probe. The central conductive wire 11 typically has a diameter of 250 microns or less at or near the connection end, and preferably less than 30 microns.The central conductor wire 10 may have a diameter of 30 micrometers or less, advantageously 20 micrometers or less, more advantageously 10 micrometers or less, even more advantageously 5 micrometers or less, or even less than 1 micrometer, at or near the probe tip. The central conductor wire 11 is encapsulated or "coated" by a tapered dielectric sheath 12. "Coated" in this description means that the dielectric material is in direct contact with the central conductor wire 11 and completely encapsulates the central conductor wire 11 over the probing portion 13 and the support portion 14. The dielectric sheath 12 is tapered such that the outer diameter of the dielectric sheath 12 is larger at the connection end of the measuring probe than at its probing end.

[0082] In particular, the dielectric sheath 12 covering the central conducting wire 11 is tapered on the probing portion 13 of the measuring probe 10. The dielectric sheath 11 can be made of glass (by "glass" is meant a material comprising silicon dioxide).

[0083] Consequently, and generally speaking, the probing portion 13 of the measuring probe 10 has a tapered shape, the dimension of its probing portion 13 decreasing in a direction from the connection end 10a to the probing end 10b. This is due to the thickness of the tapered dielectric sheath 12 around the central conducting wire 11 and to the thickness of the central conducting wire 11 itself, which vary along the probing portion 13. These thicknesses are generally decreasing along the probing portion from a direction from the connection end 10a to the probing end 10b. The typical thickness of the tapered dielectric sheath 12, on the side of the connection end 10a of the measuring probe 10, can be approximately 400 micrometers. On the side of its probing end, the thickness of the tapered dielectric sheath 12 can be less than 100 microns, or 50 microns or even less than 10 microns.

[0084] Finally, a measuring probe 10 according to the invention also comprises an electrically conductive layer 15 (hereinafter "main conductive layer 15"). This main conductive layer 15 covers the dielectric sheath 12 and partially covers at least one facet 16. The combination of the central conductive wire 11, the dielectric sheath 12, and the main conductive layer 15 forms an electrical transmission line. The main conductive layer 15 may be made of platinum, gold, or another metal. Its thickness is typically between 20 nm and 1000 nm, and preferably between 600 and 1000 nm.

[0085] As illustrated in [Fig.3], an electrically conductive layer, referred to as central zone 15a, can be formed only on at least one facet 16. The central zone 15a is electrically insulated from the main conductive layer 15, said central zone 15a covering the end of the central conducting wire 11.

[0086] According to an advantageous embodiment, the main conductive layer may comprise a peripheral section 20 formed on at least one facet 16 and electrically insulated from the central zone 15a. In particular, the peripheral section 20 may be electrically insulated from the central zone 15a by a non-conductive zone 17, and specifically, as illustrated in [Fig. 3], by a groove. In this respect, the non-conductive zone 17 delimits the central zone 15a on at least one facet 16. Furthermore, the central zone 15a may be in electrical contact with the end of the central conducting wire 11 (for example, the central zone may cover the end of the central conducting wire or be in contact via an additional wire interconnecting both the end of the central wire and the central zone). In other words, the central zone 15a is in electrical contact with the end of the central conductor wire 11 at the probing end 10b.

[0087] The measuring probe further includes a central tip 18 and at least one lateral tip 19 disposed on the facet 16, the central tip 18 and the lateral tip 19 being designed to make contact with contact pads on the plate.

[0088] In particular, the central point 18 can be formed on the central area 15a and at least one lateral point 19 can be formed on the peripheral part 20. The central point and at least one lateral point are designed to make contact with the contact pads on the wafer.

[0089] Alternatively, the central point 18 can be formed under the central zone 15a. In this respect, the central zone 15a advantageously covers the central point 18 in a conforming manner.

[0090] Alternatively or in addition, a conductive contact layer, comprising a metallic material having a Brinell hardness greater than 100, can be formed on the central tip 18 and / or on at least one lateral tip 19, advantageously the metallic material comprises at least one of the elements selected from: tungsten, titanium nitride or tungsten carbide.

[0091] According to this latter aspect, the peripheral part 20 may not be taken into account, and the conductive contact layer covering at least one lateral tip 19 may also cover the main conductive layer on the side of the dielectric sheath.

[0092] Alternatively or in addition, the central area can be omitted and the electrical contact between the central tip and the end of the central conducting wire 11 at the probing end 10b can be made by the conductive contact layer.

[0093] The conductive contact layer may comprise an electrically conductive material having a Brinell hardness greater than 100. Advantageously, the electrically conductive material comprises at least one of the following elements selected from: tungsten, titanium nitride, tungsten carbide, nickel or platinum.

[0094] As illustrated in [Fig. 3], the central tip and at least one lateral tip may have a truncated cone shape. In particular, each tip (central or lateral) may comprise a stack of discs whose diameters decrease from the base to the apex of the tip.

[0095] The height H of the central point and of at least one lateral point may be less than half the distance D separating the top of the central point and the top of at least one lateral point.

[0096] The height of the central tip and the height of the lateral tip can be between 1 and 25 micrometers, and / or the distance between the central tip and the lateral tip is between 1 and 70 micrometers, advantageously between 1 and 50 micrometers, more advantageously between 1 and 25 micrometers.

[0097] The distance between the central tip and the lateral tip can be between 1 and 70 micrometers, advantageously equal to 50 micrometers.

[0098] The central tip and the lateral tip may comprise a metallic material having a Brinell hardness (measured according to ASTM E10-14, or EN 6506-1) greater than 100. Advantageously, the metallic material comprises tungsten, platinum or nickel.

[0099] Advantageously, the at least one facet 16 comprises a main facet 16a and a lateral facet 16b, the main facet being substantially orthogonal to the direction of extension of the drilling portion, while the lateral facet 16b forms a bevel of the drilling end. The central point and the at least one lateral point are formed on the lateral facet. This latter feature facilitates contact between the points 18, 19 and the contact pads of the plate W, as can be seen in [Fig. 1]. Advantageously, the main facet is free of any metallic material.

[0100] As illustrated in [Fig.4], a central pedestal 21 of electrically conductive material is interposed between the central area 15a and the central tip 18, and a lateral pedestal 22 of electrically conductive material is interposed between the peripheral part 20 and at least one lateral tip.

[0101] The present invention also relates to a method for manufacturing a measuring probe for testing semiconductor devices on wafers, comprising:

[0102] a) insert a conducting wire into a central hole of a dielectric capillary;

[0103] b) heat and stretch the dielectric capillary over the conducting wire by separating the two ends to form a conical dielectric sheath on the conducting wire;

[0104] c) separating the conductive wire and the dielectric layer in a separation zone to obtain two separate portions, the tapered dielectric sheath covering a probing portion of a central conductive wire of each separated portion,

[0105] d) form at least one facet at a free end, referred to as the drilling end, of the drilling portion, the formation of the at least one facet being carried out in such a way that the end of the conducting wire at the drilling end is flush with the at least one facet;

[0106] e) form a main conductive layer on at least one of the separated portions, the main conductive layer covering the tapered dielectric sheath and partially covering at least one facet of the considered separated portion;

[0107] g) form a central point and at least one lateral point on at least one facet.

[0108] Figures 5a to 5d illustrate a method for manufacturing a measuring probe 10 according to the invention. In step a) shown in [Fig. 5a], an electrically conductive wire 11 is inserted into a central hole of a dielectric capillary 12'. The dielectric capillary 12' has two ends.

[0109] In a step b) shown in [Fig. 5b], the dielectric capillary 12' is heated, for example with a laser, and the two ends of the capillary 12' are separated from each other. During this step, the dielectric material (for example, glass) of the capillary 12' becomes softer and the capillary 12' is stretched over the conducting wire 11. The size of the central hole is reduced such that the dielectric material comes into contact with the conducting wire 11 at least in a tapered area of ​​the capillary 12' to form a tapered glass sheath.

[0110] The heating can be interrupted to solidify the dielectric material coating the conductive wire 11 and improve their contact. A further heating and drawing step can then be added, which tends to taper the conductive wire 11. During this further step, the dielectric sheath and the conductive wire are separated at both ends to form a tapered glass sheath on a tapered conductive wire.

[0111] During the heating and drawing step, the two ends are separated until the tapered zone breaks (step c)). Figure 5c shows the two separated portions 12a, 12b after the fracturing step of the dielectric layer and the wire 11 at the tapered / fractured zone. At this stage, each portion 12a, 12b comprises a central conducting wire 11 having a probing portion 13 encased in a tapered dielectric sheath 12 which forms the base of the measuring probe 10.

[0112] Fig. 5d is a SEM micrograph of the end of the borehole portion 13. In this figure, the conductive wire 11 protrudes from the borehole end 10b.

[0113] Step c) can be followed directly by the formation of a thin metallic layer, for example a metallic layer 200 nm thick, on the tapered dielectric sheath. The thin metallic layer can be formed by sputtering and can include gold.

[0114] The method may also include a step d) of forming at least one facet 16 at a free end, referred to as the drilling end 10b, of the drilling portion 13. The formation of the at least one facet is in particular carried out so that the end of the conducting wire at the drilling end is flush with the at least one facet.

[0115] The formation of at least one facet 16 can be a multi-step process and may involve lateral removal, in particular by means of sputtering, and more particularly by means of a plasma-focused ion beam ("PFIB").

[0116] In this regard, Figures 5e and 5f are SEM micrographs representing at least one facet. In particular, the at least one facet comprises a principal facet 16a and a lateral facet 16b. The principal facet is orthogonal to the extension direction of the borehole portion, while the lateral facet 16b forms a bevel at the borehole end. The end of the conducting wire at the borehole end is flush with the principal facet 16a or the lateral facet 16b, or both.

[0117] The method further includes the execution of a step e).

[0118] In particular, step e) includes the formation of a conductive layer on at least one of the separated portions, the conductive layer covering the tapered dielectric sheath and at least one facet of the considered separated portion. In this respect, the conductive layer has a zone, referred to as the central zone, disposed on at least one facet 16, and covering the end of the conductive wire 11 on said at least one facet. In a particularly advantageous embodiment, step e) may include the formation of the main conductive layer by masking-evaporation.

[0119] The method may also include performing a step (f). In particular, step (f) includes forming a non-conductive zone 17 (for example, a metal-free zone) within the conductive layer 15, said non-conductive zone 17 (for example, a metal-free zone) delimiting the central zone 15a of the conductive layer, said central zone 15a being electrically isolated from the rest of the conductive layer. In other words, the depth of the non-conductive zone 17 is at least equal to the thickness of the conductive layer 15. The formation of the non-conductive zone 17 may also be carried out by sputtering or etching; more advantageously, sputtering is carried out by a focused ion beam.

[0120] The method also includes performing a step g) before or after step f).

[0121] Step g) includes the formation of a central tip 18 on the central area 15a and at least one lateral tip 19 on the remainder of the conductive layer 15 formed on at least one facet 16.

[0122] Step g) can be carried out by an additive method, the tips being advantageously produced with conductive materials such as copper.

[0123] Step g) can be carried out by material removal, advantageously by focused ion beam.

[0124] In particular, each tip 18, 19 may comprise a stack of disc-shaped structures, with a diameter decreasing from the base of the tip to the apex of the tip. The respective diameters of the disc-shaped elements may be equal to 25 micrometers, 15 micrometers, 10 micrometers and 5 micrometers.

[0125] In the event that undesirable defects or structures appear during the PFIB process, additional spraying would be required.

[0126] The points 18 and 19 may be made of tungsten.

[0127] The manufacturing process may further include the execution of a step h), step h) includes the deposition of a conductive contact layer, comprising an electrically conductive material having a Brinell hardness greater than 100, on the central tip and at least one lateral tip, advantageously the electrically conductive material comprises at least one of the elements selected from: tungsten, titanium nitride, tungsten carbide, nickel or platinum.

[0128] Of course, the invention is not limited to the embodiments described and variants can be made without departing from the scope of the invention as defined by the claims.

Claims

Demands

1. A measuring probe (10), for testing semiconductor devices on wafers, extending from a connection end (10a) to a probing end (10b), the probing end (10b) forming at least one facet (16), the measuring probe (10) comprising: - a central conducting wire (11) extending from the connection end (10a) to the probing end (10b); - a dielectric sheath (12) covering the central conducting wire (11), the dielectric sheath (12) being tapered at a portion, called the probing portion (13), of the measuring probe (10), the probing portion (13) being substantially straight or curved and terminating at the probing end (10b); - a main conductive layer (15) covering at least the dielectric sheath (12) and partially at least one facet (16);the measuring probe (10) further comprises a central tip (18) and at least one lateral tip (19) located on at least one facet (16), the central tip (18) and at least one lateral tip (19) being designed to make contact with contact pads on the wafer; the measuring probe (10) further comprises an electrically conductive layer, called the central zone (15a), formed only on at least one facet (16), which is electrically insulated from the main conductive layer (15), and the central zone (15a) is in electrical contact with the end of the central conductive wire (11), the central zone (15a) ensuring electrical contact between the central tip (18) and the end of the central conductive wire (11).

2. Measuring probe (10) according to claim 1, wherein the height H of the central tip (18) and of at least one lateral tip (19) is less than half the distance D separating the top of the central tip (18) and the top of at least one lateral tip (19).

3. Measuring probe (10) according to claim 1 or 2, wherein the central tip (18) and at least one lateral tip (19) have the shape of a truncated cone or several truncated cones.

4. Measuring probe (10) according to any one of claims 1 to 3, wherein the height of the central tip (18) and the height of the lateral tip (19) is between 1 micrometer and 25 micrometers, and / or the distance between the central tip (18) and the lateral tip (19) is between 1 micrometer and 70 micrometers, advantageously between 1 micrometer and 50 micrometers, more advantageously between 1 micrometer and 25 micrometers.

5. Measuring probe (10) according to any one of claims 1 to 4, wherein the central tip (18) and the lateral tip (19) comprise a conductive material having a Brinell hardness greater than 100, advantageously, the conductive material comprises tungsten, platinum, tungsten carbide, titanium nitride or nickel.

6. Measuring probe (10) according to any one of claims 1 to 5, wherein the dielectric sheath (12) comprises glass and / or wherein the central conducting wire (11) comprises a platinum-iridium alloy material, and / or wherein the main conducting layer (15) comprises at least one of the elements selected from: gold, platinum, tungsten.

7. Measuring probe (10) according to any one of claims 1 to 6, wherein the central conducting wire (11) has, at the probing end (10b), a diameter less than or equal to 30 micrometers, advantageously less than or equal to 20 micrometers, more advantageously less than or equal to 10 micrometers, even more advantageously less than or equal to 5 micrometers, and even less than 1 micrometer.

8. Measuring probe (10) according to any one of claims 1 to 7, wherein at least one facet (16) comprises a main facet (16a) and a lateral facet (16b), the main facet (16a) being substantially orthogonal to the extension direction of the sounding portion (13), while the lateral facet (16b) forms a bevel of the sounding end (10b), advantageously the main facet (16a) is substantially free of any electrically conductive material.

9. Measuring probe (10) according to claim 8, wherein the central tip (18) and at least one lateral tip (19) are formed on the lateral facet (16b).

10. Measuring probe (10) according to any one of claims 1 to 9, wherein the main conductive layer (15) comprises a peripheral section (20) formed on at least one facet (16), and on which is formed at least one lateral tip (19).

11. Measuring probe (10) according to any one of claims 1 to 10, wherein the central area (15a) is interposed between the central tip (18) and at least one facet (16).

12. Measuring probe (10) according to claim 11, wherein the central area (15a) is electrically isolated from the main conductive layer (15) by a non-conductive area (17).

13. Measuring probe (10) according to any one of claims 1 to 12, wherein a conductive contact layer, comprising an electrically conductive material having a Brinell hardness greater than 100, is formed on the central tip (18) and / or the lateral tip (19), advantageously the electrically conductive material comprises at least one of the elements selected from: tungsten, titanium nitride, tungsten carbide, nickel or platinum.

14. Method of manufacturing a measuring probe (10) for testing semiconductor device wafers, comprising: a) inserting a conductive wire into a central hole of a dielectric capillary; b) heating and stretching the dielectric capillary over the conductive wire by separating the two ends to form a tapered dielectric sheath (12) over the conductive wire; (c) separate the conductive wire and the dielectric layer in a separation zone to obtain two separate portions, the tapered dielectric sheath (12) covering a probing portion (13) of a central conductive wire (11) of each separated portion, (d) form at least one facet (16) at a free end, referred to as the probing end (10b), of the probing portion (13), the formation of at least one facet (16) being carried out so that the end of the conductive wire at the probing end (10b) is in contact with the at least one facet (16);e) form a main conductive layer (15) on at least one of the separated portions, the main conductive layer (15) covering the tapered dielectric sheath (12) and partially at least one facet (16) of the considered separated portion; g) form a central point (18) and at least one lateral point (19) on at least one facet (16); said manufacturing process further comprises a step f) of forming an electrically conductive layer, referred to as the central zone (15a), formed only on at least one facet (16); which is electrically isolated from the main conductive layer (15) and which establishes electrical contact with the end of the central conductive wire (11).

15. A manufacturing method according to claim 14, wherein step e) comprises the formation of an electrically conductive layer on the conical dielectric sheath (12) and at least one facet (16), and step f) is a partial removal of the electrically conductive layer to form a non-conductive area on at least one facet (16), advantageously, the removal is carried out by spraying or etching, more advantageously the spraying is carried out by focused ion beam.

16. A manufacturing method according to any one of claims 14 to 15, wherein step g) is carried out by an additive method, advantageously the tips are produced with conductive materials such as copper.

17. A manufacturing method according to any one of claims 14 to 15, wherein step g) is accomplished by material removal, advantageously by focused ion beam.

18. A manufacturing method according to any one of claims 14 to 17, wherein said manufacturing method further comprises carrying out a step h), step h) comprises the deposition of a conductive contact layer, comprising an electrically conductive material having a Brinell hardness greater than 100, on the central tip (18) and at least one lateral tip (19), advantageously the electrically conductive material comprises at least one of the elements selected from: tungsten, titanium nitride, tungsten carbide, nickel or platinum.

19. A manufacturing method according to any one of claims 14 to 18, wherein step e) of the main conductive layer (15) is deposited by masking-evaporation.

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