WO2006082295A1

WO2006082295A1 - Method for testing electrical conductors by photoelectric effect, using a separator plate

Info

Publication number: WO2006082295A1
Application number: PCT/FR2006/000157
Authority: WO
Inventors: Christophe Vaucher
Original assignee: Beamind
Priority date: 2005-02-04
Filing date: 2006-01-24
Publication date: 2006-08-10
Also published as: FR2881832A1; TW200641378A; FR2881832B1; EP1844345A1

Abstract

The invention concerns a method for testing or measuring electrical elements (10) including steps of injecting electrons into the elements to be tested or ejecting electrons present in the elements to be tested, using at least one beam of particles and an electron discharge or collecting plate (20) arranged above the elements to be tested and comprising electron discharge or collection electrodes. The invention is characterized in that an electrically insulating separator plate (30) is arranged between the discharge or collecting plate (20) and the elements to be tested, and comprises orifices (31) at locations corresponding to electron injection or collection points.

Description

METHOD FOR TESTING ELECTRICAL CONDUCTORS

BY PHOTOELECTRIC EFFECT, MEDIUM

A SEPARATING PLATE

The present invention relates to the non-contact electrical test of electrical elements using the photoelectric effect, in particular the test of the electrical conductors present on the interconnection supports, but also the testing and measurement of electrical conductors, electrical or electronic components .

Electrical testing of interconnect media is a major issue in the modern electronics industry and is an integral part of the interconnect media manufacturing process. The two essential test sequences to be conducted to verify that an interconnect conductor does not exhibit a manufacturing defect are the continuity test and the insulation test. The continuity test consists in checking that the conductor is not cut between its ends, more precisely between the connection points that it connects. It is generally a question of measuring the resistance of the conductor between connection points of the conductor (contact pads) and of making sure that it is very weak (typically of the order of one ohm). The isolation test is intended to ensure that each conductor of an interconnect carrier is electrically isolated from other conductors.

With the miniaturization and complexification of integrated circuits made in the form of silicon chips, interconnect carriers have a growing complexity in the image of that of the integrated circuits they host. Thus, the high density interconnect carriers have conductors whose width and length are constantly decreasing, and the surface of their connection points with integrated circuits. Because of this, the test methods Conventional, using spiked cards or nail beds are becoming more and more inadequate.

To overcome these drawbacks, in recent years non-contact test methods have been developed in which the photoelectric effect is used to act on the electrical potential of the conductors to be tested and thus conduct isolation and continuity test sequences. The photoelectric effect is caused by applying to a conductive material a beam of particles having sufficient energy to impart to the electrons of the conduction layer of the target material an energy at least equal to their work function ("work function"). The electrons are then torn - ejected - from the conductive material and are then accelerated by an intense electric field (several million volts per meter). For the sake of simplification of the language, the term "photoelectric effect" is here generic and denotes a phenomenon of tearing or ejection of electrons from a target material. In fact, with materials such as copper, gold, or lead tinned conductors, short wavelength coherent light sources, especially ultraviolet light sources, are generally used, but sources of Non-coherent light are also used as well as particles other than photons, for example an ion beam or an electron beam. Historically, as illustrated for example by US patents 6, 369, 590 and US 6,369,591, the photoelectric effect has been used to tear electrons present in a conductor to be tested. Since it is generally not desired - or possible - to access the driver to apply a negative electric potential that would create a repulsive electric field at the time of ejection of electrons (the driver is generally at a floating potential), a collection electrode raised to a positive potential solves this problem by generating a powerful electric field that attracts electrons ejected by the driver. The collection electrode also allows the collection and counting of the quantity of electricity extracted from the conductor to deduce, for example, its initial electrical potential.

International application WO 01/38892 provides a major improvement to the test methods based on the photoelectric effect, by providing an electron injection into a conductor in addition to an extraction of electrons present in a conductor.

FIGS. 1A and 1B respectively illustrate the injection of electrons into a conductor and the ejection of electrons present in a conductor according to the method described in the aforementioned international application. The injection and ejection of electrons are carried out by means of a discharge and collection plate 5 comprising electron-discharge electrodes 6 (electron-emitting electrodes) and electron-collecting electrodes. 7 (FIG IB) arranged on a support plate 8, a single electrode of each category being shown in the figures. The support plate 8 is transparent or partially transparent to a beam of particles Bl photoelectric effect generator. The particle beam B1 is, for example, an ultraviolet light beam and the support plate 8 is, for example, made of silica.

In FIG. 1A, a conductor 1 arranged on a dielectric substrate 2 has a contact pad 3 ("pad contact") delimited by a savings zone made in a protective varnish 4. The pad 3 is used as a test point of the conductor 1, that is to say as target area for the injection of electrons into the conductor. The discharge electrode 6 is disposed opposite the range 3, at a distance d thereof. The discharge electrode 6 is brought to a negative electrical potential Vn less than a floating potential Vf of the conductor 1, and its rear face is bombarded by the light beam B1, through the support plate 8 and in the presence of a primary vacuum. Electrons are ejected from the front face of the discharge electrode 6 and are projected onto the conductor 1 under the action of the repulsive electric field E = (Vn-Vf) / d generated by the negative potential of the discharge electrode . In FIG. 1B, a conductor arranged on the same dielectric substrate 2 has a contact area 3 'delimited by a savings zone made in the protective varnish 4. The range 3' is used as a test point of the driver 1, here as a target zone for the ejection of electrons present in the driver. The collection electrode 7 is arranged facing the target range 3 ', at a distance from it, substantially identical to the distance d. The collector electrode 7 is brought to a higher electric potential Vp ^• positive floating potential Vf of the driver 's, and the track 3 is bombarded by the Bl light beam through the support plate 8 and presence of a primary vacuum. Electrons are ejected by the range 3 'and are collected by the collection electrode 7 under the action of the attractive electric field E = (Vp-Vf) / d' generated by the positive potential of the collection electrode.

In both cases, injection or ejection of electrons, electrons are exchanged between the conductor and the electrodes until the potential of the conductor is equal to the potential of the discharge or collection electrode. The method thus makes it possible to bring the floating potential of the conductor to the voltage Vn of the discharge electrode or to the voltage Vp of the collection electrode, for example to carry out an insulation test. It also allows a current to flow in a conductor, injecting electrons at a first point of the conductor and ejecting electrons at a second point of the conductor. If, for example, the conductor of FIG. 1B and the conductor 1 of FIG. 1A are the same conductor, and the tracks 3, 3 'have two ranges of this same conductor, a current flows in the conductor if electrons are injected on the range 3 and electrons are ejected from the 3 'range. The measurement of the current or electrical charges exchanged makes it possible to conduct a continuity test or to carry out a resistance measurement.

This method, however, has disadvantages. On the one hand, the electron beam must be channeled so that electrons circulating between the discharge electrode and the target conductor or between the target conductor and the collection do not reach neighboring conductors or adjacent electrodes. This disadvantage is solved in the aforementioned international application by bringing to a repulsive electric potential of the electrodes adjacent to the discharge or collection electrodes, so as to form electron circulation corridors delimited by a repulsive electric field. However, this solution requires bringing the repulsive potential to the relevant electrodes, which implies the provision of a relatively complex electrode addressing and multiplexing system and also complicates the structure of the discharge and collection plate.

On the other hand, the distance d or between the target conductor and the discharge or collection electrode, of the order of a few tens to a few hundred micrometers, must be precisely controlled and must not vary during a test sequence. For this purpose, the positioning means of the discharge and collection plate are used with great precision, but expensive to produce and complex to use.

Thus, the present invention provides a specific means for facilitating the implementation of the method of injection or ejection of electrons by photoelectric effect described above, and to improve the performance of this process.

The present invention also relates to a method of injection and ejection of electrons by photoelectric effect which uses the specific means according to the invention.

In a simple but no less inventive way, the means of the invention is an electrically insulating material arranged around the electron circulation paths, for example an insulating plate comprising orifices arranged at locations corresponding to injection or injection points. ejection of electrons. Such an insulating plate, when arranged between a discharge or collection plate and elements to be tested, also forms a spacer which makes it possible to wedge the distance between the electrodes of the discharge and collection plate and the target zones of the elements to test. Various other advantages will be described in the following. Thus, the present invention provides a method for injecting electrons into an electrical element or ejecting electrons present in the electrical element, comprising the steps of disposing in proximity to the element at least one electron discharge electrode or electron collection electrode, carry the electrode to a first electrical potential, and apply a particle beam to the electrode or element, so that electrons are torn from the electrode or element and reach the element or electrode, in which the electrons circulating between the electrode and the element, or between the element and the electrode, are channeled by an electrically insulating material arranged around an electron circulation zone .

According to one embodiment, the electrons circulate in an orifice made in an electrically insulating separator plate.

According to one embodiment, the separator plate comprises at least one metal region opening into the orifice, and the metal region is brought to an electric potential.

According to one embodiment, the metal region is a metal layer pierced with the orifice, forming a kind of metal ring on the walls of the orifice.

According to an embodiment relating to the injection of electrons into the element, the method comprises applying to the electrode a reflected particle beam from the incident particle beam applied to the element and reflecting on this one.

According to one embodiment, the particle beam is a beam of ultraviolet light.

According to one embodiment, the electrical element is a conductive track, a track of a conductive track, an electrical or electronic component or a terminal of an electrical or electronic component. The invention also relates to a method for testing or measuring electrical elements comprising electron injection steps in elements to be tested or to ejection of electrons. present in elements to be tested, by means of at least one particle beam and an electron collection or discharge plate arranged above the elements to be tested and comprising discharge or electron-collecting electrodes method in which an electrically insulating separator plate is arranged between the discharge or collection plate and the elements to be tested, and includes orifices at locations corresponding to electron injection or collection points. According to one embodiment, the separator plate comprises at least one metal region opening into the orifices, and the metal region is brought to an electric potential.

According to one embodiment, the discharge or collection plate comprises electrodes of the same structure, each of which can form a discharge electrode or a collection electrode.

According to one embodiment, the discharge or electron collection plate comprises electrodes arranged in a matrix manner, in rows and in columns.

According to one embodiment, the discharge or collection plate comprises electrodes in the form of conductive strips parallel to each other.

According to one embodiment, an electrical element is at least one of the following elements: an electrical conductor, an electrical component, an electronic component, a terminal of an electrical conductor or a terminal of an electrical or electronic component.

The invention also relates to a method for manufacturing an interconnection support or an electronic circuit arranged on an interconnection support, the interconnection support or the electronic circuit comprising electrical elements, the method comprising a step of test or measurement of all or part of the electrical elements of the interconnection support or electronic circuit implemented according to the test or measurement method according to the invention.

The invention also relates to a device for testing or measuring electrical elements comprising at least one source of a particle beam, at least one discharge or electron collection plate comprising electrodes that can be individually carried to potentials. electrodes for injecting electrons into elements or for collecting electrons ejected from the elements, and an electrically insulating separator plate disposed or arranged between the discharge or collection plate and the elements to be tested, the separator plate comprising orifices at locations corresponding to electron injection points in the elements or electron ejection points present in the elements and forming electron circulation corridors.

According to one embodiment, the separator plate comprises at least one metal region opening into the orifice.

According to one embodiment, the device comprises a source of potential for applying an electric potential to the metal region.

According to one embodiment, the metal region is a metal layer pierced with the orifice, forming a kind of metal ring on the walls of the orifice. According to one embodiment, the device is arranged to apply a beam to an electrode. of reflected particles from the incident particle beam applied to and reflective of an element for ejection of electrons from the electrode and injection into the element. According to one embodiment, the electron discharge or collection plate comprises electrodes of the same structure, each of which can form a discharge electrode or a collection electrode.

According to one embodiment, the discharge or collection plate comprises the conductive zones arranged in a matrix manner, in rows and in columns. According to one embodiment, the discharge plate or electron collection comprises conductive zones in the form of strips parallel to each other.

According to one embodiment, the particle beam is a beam of ultraviolet light.

These and other objects, features and advantages of the present invention will be set forth in more detail in the following description of exemplary embodiments of a separator plate according to the invention, a method and a test device. using such a separating plate, made in a nonlimiting manner in relation to the attached figures in which: Figures IA, IB previously described respectively illustrate a conventional method of injecting electrons into a conductor and ejecting electrons present in the driver,

FIG. 2 is a view from above of a separator plate according to the invention,

FIG. 3A is a sectional view of the separating plate of FIG. 2 according to a first embodiment,

FIG. 3B is a sectional view of the separating plate of FIG. 2 according to a second embodiment,

- Figure 4 shows a device for injecting and ejecting ^• electron using the separator plate according to the invention, - Figures 5A and 5B illustrate respectively the injection of electrons in a conductor and the ejecting electrons present in one. conductor by means of the device of Figure 4,

FIG. 6 illustrates the implementation of a continuity test by means of the method according to the invention; FIG. 7 represents in the form of blocks a test device according to the invention as well as an exemplary embodiment of a discharge or collection plate according to the invention, and - Figure 8 shows another embodiment of a discharge plate or collection according to the invention.

Figure 2 is a top view of a separator plate 30 according to the invention. The separator plate 30 is made of an electrically insulating material and has openings 31 (31- I ₇ 31-2, 31-3, 31-4, 31-5 ... 31-i) which pass through the plate 30 on either in part. The plate 30 is intended to be arranged between a discharge plate or electron collection and elements to be tested or measured. The thickness of the plate 30 thus corresponds to the desired distance between the discharge or collection electrodes and the elements to be tested or measured (conductors, electrical or electronic components or terminals of such components). The orifices 31 are arranged at locations corresponding to the points of injection or ejection of electrons. The openings 31 and their insulating material walls form electron circulation corridors preventing them from reaching neighboring target areas or reaching neighboring discharge or collection electrodes.

FIG. 3A is a sectional view of the plate 30 along an axis AA 'passing through the orifices 31-1 to 31-4 and according to a first embodiment 30 (A). The plate 30 is here made in a single layer or block of electrically insulating material, but may also be formed of a stack of insulating layers. The plate 30 is for example made with one of the materials used in the printed circuit industry to form the substrates of the interconnection circuits, for example epoxy glass, RCC ("Resin Coated Core") or Kapton . The material may be rigid or flexible. In the second case, the plate 30 forms a kind of insulating film. The plate 30 is cut and the orifices 31 are machined using conventional equipment such as mechanical or laser drills or milling / trimming equipment.

FIG. 3B is a sectional view of the plate 30 along the axis AA 'and according to a second embodiment (B) in which the plate 30 is provided with one or more conductive cores, here three conductive cores. The plate 30 is made of several layers of the electrically insulating material, here four insulating layers 300, 301, 302, 303. a conductive layer 310 forming the first conductive core is arranged between the insulating layers 300 and 301. a conductive layer 311 forming the second conductive core is arranged between the layers 301 and 302. conductive layer 312 forming the third conductive core is arranged between the layers 302 and 303. The conductive layers 310, 311, 312 are connected to an external contact terminal 320. They are pierced at the locations through which the orifices 31 and thus form, seen from the inside of the orifices 31, kinds of metal rings which are flush with the walls of the orifices 31. The conductive core plate is manufactured by stacking and lamination of the insulating layers with the conductive layers, which are preferably metal layers, in using the manufacturing processes of the printed circuit industry. The stacks are then machined in the same manner as the separator plate without a conductive core. The conductive layers 310, 311, 312 form, seen from the inside of the orifices 31, kinds of metal rings. The contact terminal 320 makes it possible to connect them to a source of electrical potential providing a potential Vec.

The potential Vec can be used for many purposes. If it is chosen negative, it has a repulsive effect on the electrons and makes it possible to focus the electron beam crossing the orifices 31. If it is chosen positive, it creates an accelerating electric field allowing to prevent the formation of a space charge that could slow down the flow of electrons, or at least limit the formation of such a load of space. A zero potential Vec (mass) can also be used to evacuate electrons that could stick along the walls of the orifices.

A space charge is formed by a cloud of electrons that may appear when the number of electrons collected per unit of time (current) by a collection electrode or supplied per unit time by a discharge electrode exceeds a certain number of electrons. threshold. Charges can then accumulate along the walls of the orifices 31, which can create a throttling of the circulation of electrons. Theoretical calculations confirm that the current collected by the photoelectric effect is limited by the space charge created by the transit charges. The greater the distance between the discharge or electron collection electrodes, the greater the number of charges in transit at a given moment is important. The use of the separator plate with conductive core (s) is thus advantageous when the distance between the discharge or collection electrodes and the test points is important. In practice, one can choose to minimize the distance between the electrodes and the test points to increase the current and thus the efficiency of the process, or to prevent the formation of the space charge by using the core separator plate. polarized conductor (s). In the second case, the electrons ejected with a determined initial velocity are rapidly removed by the combination of their initial velocity and the accelerating electric field created by the positive positive voltage Vec, to which is added the repulsive field of the discharge electrode or the attractive field of the collection electrode. The separator plate 30 according to the invention is capable of various uses. It can for example be used to implement the conventional method of ejection and electron injection illustrated in Figures IA, IB. The plate 30 is then arranged between the conductors 1, 1 'and the discharge and collection plate 5. A first orifice is provided between the range 3 and the discharge electrode 6 and a second orifice is provided between the 3' range. and the collection electrode 7 for channeling the electron fluxes.

An ejection and electron injection process using an "indirect" photoelectric effect will be described in the following, as an example of a preferred embodiment of the separator plate according to the invention.

This process is based on the observation that the metals or materials conventionally used to form the interconnecting conductors or cover them, or those used to form the contact terminals of electrical or electronic components, in particular copper, gold , the tin solder with or without ploπib, have a good reflection coefficient - generally of the order of 30 to 85% - vis-a-vis the particle beams used to cause the photoelectric effect, especially ultraviolet light beams. Thus, the basic idea of this method is to extract electrons present in a discharge electrode, by means of a reflected particle beam from an incident beam applied to the target element and reflecting on it. instead of applying the particle beam to the rear face of the discharge electrode. The discharge electrode is thus struck by the particle beam on its front face (by convention that which is opposite the target conductor) instead of being struck on its rear face.

A test bench of electrical elements implementing this method is illustrated by a sectional view in FIG. 4. The test bench comprises:

the elements to be tested or measured, here conductors 10, 10 ',

a discharge or collection plate 20, at least one source of a beam of particles that is orientable towards any point of the discharge or collection plate, in this case an ultraviolet light beam B 1,

a separator plate 30 according to the invention arranged between the substrate 12 and the discharge or collection plate 20. The conductors 10, 10 'are arranged on an electrically insulating substrate 12 and have contact pads 11A, 11A' (" contact pads ") defined by zones of savings in a protective varnish 13, the contact pads forming test points or target areas for the injection or the ejection of electrons (also called in the following zones of photoelectric impact).

The discharge or collection plate 20 comprises a silica support plate 21 that is transparent or partially transparent to ultraviolet rays, the front face of which (electrically conductive 10, 10 ') comprises electrodes 22 that are individually accessible for application to each electrode. an electric potential. The incident light beam B1 is applied on the rear face of the support plate 21, at a given angle of incidence which is here perpendicular to the plate 21, and through the support plate 21 to reach the areas of photoelectric impact. The support plate 21 is kept parallel to the substrate 12 by the separating plate 30, so that the conductor 10 is at a distance d from the electrodes 22 along an axis perpendicular to the plane of the substrate 12.

The separator plate 30 according to the invention has a thickness d corresponding to the desired distance between the electrodes 22 and the zones of photoelectric impact. It has as previously orifices at the locations corresponding to the test points of the conductors 10, 10 'and in particular the orifices 31, 31' arranged between the surfaces 11A, 11A 'and electrodes 22 lying opposite these areas. Although the plate 30 shown is formed by a single layer of insulating material, it may also include one or more conductive cores connected to the potential Vec, as indicated above.

The electrodes 22 are here of the same structure, each of which can form a discharge electrode or a collection electrode. Each electrode comprises a thin layer of metal of a thickness of the order of a few hundred nanometers deposited on the support plate 21. The electrodes 22 are arranged here in a matrix manner (in rows and columns) and are connected by conductors (not shown) for individually applying electrical potentials. The shape and size of the electrodes and their spacing are chosen so that the incident beam B passes partially through the discharge or collection plate 20 and reaches the target areas. For example, an arrangement of the electrodes 22 considered satisfactory is such that about 30 to 60% of the incident beam B 1 reaches the target areas, the remainder of the beam B 1 being reflected or absorbed by the rear face of the electrodes 22. For this purpose, the electrodes 22 are here of a width less than that of the contact pads 11A, 11A 'so that several electrodes are in the immediate vicinity of the beaches 11A, 11A' while others are outside the impact zones photoelectrical, and are masked by the separator plate 30. However electrodes provided with one or more windows for the passage of the light beam B1 can also be provided. FIGS. 5A, 5B are expanded views of FIG. 4 in the vicinity of the range 11A of the conductor 10. FIG. 5A illustrates a step of electron injection in the conductor 10 and FIG. 5B illustrates a step of ejection of electrons present in the conductor 10. The two steps are implemented by means of the light beam B1 in the presence of a primary vacuum (partial vacuum).

In FIG. 5A, the electrodes 22 are brought to an electrical potential Vn less than the electrical potential Vf of the conductor 10, which is a floating potential. If necessary, the potential Vf may be initialized beforehand to a known value greater than Vn. The conductor 10 may for example be grounded or brought to a positive potential by various known means (carbon brush, ion bombardment) or by means of the electron ejection step shown in FIG. 5B and described below. The electrical potential Vn is for example a voltage of the order of 0 to -5V. The incident light beam B1 is reflected on the range 11A of the conductor 10 to form a reflected light beam BR which is reflected back onto the electrodes 22. A double photoelectric effect is thus observed: 1) the first photoelectric effect or "direct photoelectric effect" "is produced by the impact of the incident beam B1 on the range 11A and leads to the ejection of electrons of type" el "which are returned to the conductor 10 due to the repulsive electric field E = (Vn-Vf) / d which prevails between the electrodes 22 and the conductor 10.

2) the second photoelectric effect or "indirect photoelectric effect" is produced by the impact of the reflected beam BR on the electrodes 22 and leads to the ejection of "e2" type electrons which are projected onto the conductor 10 by the field electrical repellent and are absorbed by it.

Thus, the conductor 10 is negatively charged (load of its parasitic capacitance) and its electrical potential tends towards the 22. At the end of the process, the conductor 10 is at the potential Vn. The duration of the process is typically of the order of a few nanoseconds and determines the duration of a photoelectric shot. In FIG. 5B, the electrodes 22 opposite the range 11A of the conductor 10 are brought to an electrical potential Vp greater than the electrical potential Vf of the conductor 10, for example a positive voltage of the order of 1 to 5V. If necessary, the potential Vf is initialized to a value less than Vp, for example the ground potential or the potential Vn obtained by means of the electron injection step. As previously, a portion of the intensity of the incident light beam B1 is reflected on the range 11A of the conductor 10 to form a reflected light beam BR which is returned to the electrodes 22. Thus, a direct and indirect photoelectric effect is observed again. an indirect photoelectric effect, but here the direct photoelectric effect is preponderant whereas the indirect photoelectric effect is neutralized in its effects by the attractive electric field E '= (Vd-Vf) / d which reigns between the electrodes 22 and the driver 10. Thus, the impact of the incident beam Bl on the range 11A of the conductor 10 causes the tearing of electrons of type "el" which are projected on the electrodes 22 because of the attractive electric field, while the impact on the electrodes 22 of the reflected light beam BR lead to the ejection of electrons of type "e2" which are returned to the electrodes 22 by the attractive electric field. Thus, the conductor 10 loses electrons and its electrical potential tends towards the potential Vp of the electrodes 22. At the end of the process, the conductor is at the potential Vp. The separator plate 30 offers various advantages here: i) it prevents the electrons circulating between the range 11A and the electrodes 22 or vice versa from reaching the adjacent conductors or reaching the neighboring electrodes 22 (electrodes masked by the plate 30) and as such it replaces the repulsive electric field used in the prior art, ii) it prevents light rays reflected on the range 11A from reaching electrodes 22 not to intervene in the direct or indirect photoelectric effect (electrodes masked by the plate 30), which is an advantage that can not bring the use of a repulsive electric field, iii) it also prevents light rays reflected on the electrodes 22 (second reflection after the reflection on the range 11A) to reach neighboring conductors (not visible on sectional views), iv) it allows to adjust precisely the distance d between the electrodes 22 and the target areas, v) if the conditions are such that a space charge can appear (depending on the thickness d of the separating plate and the intensity of the electron flow), the prediction of one or more conductive cores makes it possible to solve this problem, the conductive cores being brought to a slightly positive voltage Vec. vi) since it is no longer necessary to provide a repulsive electric field for channeling the electrons, it allows for a discharge or collection plate that uses only the two primary voltages Vn and Vp. This results in a simplification of the structure of the discharge or collection plate which then comprises only conductors ensuring the supply of the two primary voltages Vn, Vp to discharge or collection electrodes.

A driver isolation test sequence 10 will now be described by way of example. Consider that the insulation of the conductor 10 should be tested relative to the conductor 10 '. The isolation test sequence is for example carried out as follows: i) the conductor 10 is first brought to a reference voltage, for example ground, in a conventional manner

(for example with a carbon brush) or by using the indirect or direct photoelectric effect, then is left floating, ii) the conductor 10 is then brought to the voltage Vp by direct photoelectric effect, bringing the electrodes 22 to the potential Vp and applying to the conductor 10 a shot of ultraviolet light, iii) the conductor 10 'is grounded, in the same manner as the conductor 10, then is left floating, iv) after a lapse of time, a firing of ultraviolet light is performed on the conductor 10', bearing the electrodes 22 at the potential Vp. The electrons flowing between the electrodes 22 and the conductor 10 'are counted to determine the amount of electricity exchanged Q.

If the measured quantity of electricity Q corresponds to a quantity of reference electricity Qr determined during a calibration step, it can be deduced that the conductor 10 'was still at ground potential at the moment of firing, so that its isolation from the driver 10 is assured (and vice versa). If the quantity of electricity Q is zero, it means that the electrical potential of the conductor 10 'has passed from the voltage 0 to the voltage Vp for the aforementioned period of time because of an insulation fault. In the case of a quantitative isolation test or an insulation resistance measurement, the measured quantity Q and the duration of the time allow the insulation resistance between the conductors 10, 10 'to be determined by referring to charts, and to decide if it is above or below a rejection threshold of the circuit.

This two - conductor isolation test method is intended to be iteratively applied to sets of conductor pairs to be tested. It is capable of various alternative embodiments, particularly with regard to the electrical potentials used.

A test sequence of the electrical continuity of the conductor 10 is shown in FIG. 6. The test is conducted between the contact pad 11A of the conductor 10 and a contact pad 11B present at another end of the conductor. The electrodes next to the beach 11A. are designated 22a and those opposite the end 11B are designated 22b. The separator plate 30 has an electron circulation orifice 3IA between the range 11A and the electrodes 22a (already described under the reference 31) and an electron circulation orifice 3IB between the range 11B and the electrodes 22b. The electrodes 22a are brought to the potential Vn by a voltage source VGE1N1, via an AMCT1 circuit for acquiring and measuring the electrons flowing between the voltage source VGEN1 and the electrodes 22a. The electrodes 22b are brought to the potential Vp by a voltage source VGEN2, via an AMCT2 circuit for acquiring and measuring the electrons flowing between the electrodes 22b and the voltage source VGEN2. The test sequence also uses two sources S11, S2 of ultraviolet light and two motorized mirrors whose orientation is controlled by a CMU control and measurement unit. The measuring circuits AMCT1, AMCT2 are connected to the CMU for the evaluation of the measurement results.

The source S1 provides an incident light beam BI1 which is sent by the mirror M1 over the range 11A and the source S2 provides an incident light beam B12 which is sent by the mirror M2 over the range 11B. Thus, the range 11A is pulled towards the potential Vn by indirect photoelectric effect (electron injection) while the range 11B is pulled towards the potential Vp by direct photoelectric effect (ejection of electrons), and electrons circulate in the conductor . The electric charge Q collected by the range 11B is preferably measured in differential mode by the circuits AMCT1, AMCT2 (respectively load injected in the range 11A and load extracted from the range 11B) in order to detect possible parasitic phenomena which could cause a loss. and / or an injection of electrical charges into the test loop. Charts developed during a calibration phase allow the CMU unit to deduce the value of the R series resistor of the conductor 10, which is a function of the collected charge. Thus, the continuity test method can be used as a resistance measuring method, independently of the test of interconnection conductors, for example for the measurement of resistive components. According to the same principle, a capacitance value "C" can be measured between two conductors by applying the relationship between the capacitance, the electric charge "Q" and the applied voltage "V" (Q = CV). Also, a self-inductance value can be measured. Although the examples described here are relative to the conductor test, it will be clear to those skilled in the art that the invention also applies to the testing of electrical components or to the measurement of their electrical properties (resistances, capacitors and capacitors). self-inductances). Such components may be tested in an isolated configuration or attached to or integrated with an interconnect carrier. The photoelectric effect particle beam can be applied directly to the terminals of the components to be tested or to interconnecting conductive tracks to which these components are connected (so-called "in situ" test, once the components are mounted). The invention also applies to testing or measuring active electronic components. These are indeed modeled as a set of passive components, a MOS transistor being for example modeled in a soïïme capacitances and resistances. Thus, the injection / extraction of electrical charges on terminals of an active component makes it possible to determine the electrical characteristics of the component. It is carried out by means of a discharge or collection plate which comprises electrodes of shape and arrangement adapted to the terminals of the components.

FIG. 7 represents in block form the general architecture of a test device 40 according to the invention. The device 40 comprises: the control unit CMCJ previously described, for example a microcontroller,

the discharge or collection plate 20,

the ultraviolet light sources Sl, S2 previously described (not shown in the figure); the motorized mirrors Ml, M2 previously described (not shown in the figure),

the AMCT1, AMCT2 circuits previously described,

the voltage sources VGE-N1, VGEN2 previously described,

a line decoder LDEC1, and two column decoders CDEC1, CDEC2.

The decoder CDEC1 is electrically powered by the generator VGEN1, via the AMCTl circuit. The The CDEC2 decoder is electrically powered by the VGEN2 generator, via the AMCT2 circuit.

The discharge or collection plate 20 comprises a plurality of electrodes 22 arranged in rows of rank i and rank columns j, with only four electrodes 22 being shown in the figure. Each electrode 22 here comprises:

a metal strip 220 forming the actual electrode, for emitting or collecting electrons, here of square shape and formed by a grid of thin conductors (a monobloc layer of metal deposition may also be provided),

a transistor-switch 221 whose control gate is connected to an output of the decoder LDEC1 via a selection line LSELIi, the drain of which is connected to an output of the decoder CDEC1 via a line CSELIj selection source whose source is connected to the electrode 220,

a transistor-switch 222 whose control gate is connected to an output of the decoder LDEC1 via a selection line LSEL2i, the drain of which is connected to an output of the decoder CDEC2 via a line CSEL2J selection source whose source is connected to the electrode 220,

a measurement capacitor CS connecting the electrode 220 to a reference potential, here the voltage Vn present on the line CSEL2J. This capacitance CS is for example the parasitic capacitance of one of the transistors 221, 222 or the parasitic capacitance resulting from the two transistors. It forms a means of temporarily storing the charges collected during a firing and allows the AMCT1, AMCT2 circuits to measure quantities of electricity exchanged by photoelectric effect. Thus, once a photoelectric firing is carried out, the charge stored in the capacitor CS is emptied by grounding the conductor CSEL2j, to recover and measure the charge Q taken during the firing, which makes it possible, as indicated above, to deduce a series resistance value.

In order to select electrodes 22 and to apply to the selected electrodes one of the voltages Vp and Vn, the unit CMU supplies the decoder LDEC1 with a line address signal ADL1, which designates all the lines LSELI 1 to be activated in order to make the transistors-switches connected to these lines, and a line address signal ADL2 which designates the set of lines LSEL2i to be activated to make pass transistors-switches connected to these lines.

The CMJ also provides the decoder CDEC1 with a column address signal ADCl which designates all the lines CSELIj to receive the voltage Vp, and the decoder CDEC2 a column address signal ADC2 which designates the set of lines. CSEL2J to receive the voltage Vn. Such multiplexed addressing using voltages Vp, Vn as column select signals enables the CMU to independently apply to each of the electrodes one of the aforementioned voltages.

FIG. 8 represents a discharge or collection plate 200 according to the invention in which the electrodes 22 previously described are replaced by conductive strips 230-1, 230-2, ... 230-i parallel to each other and here in the form of rectilinear zigzag conductor strips, "Z", "S" ... can also be provided. The structure of the discharge or collection plate is thus considerably simplified. The strips 230-i forming discharge or collection electrodes are controlled by voltage and selection by a line decoder LDEC2 receiving the voltages to be multiplexed Vp, Vn and two address signals ADL1, ADL2 designating the bands to receive the voltage Vp and the strips to receive the voltage Vn; Such a discharge or collection plate 200 allows, as the previous one, to conduct insulation and continuity tests on various types of elements.

For example, consider that an insulation test must be conducted between two conductive pads C43, C44 belonging to equipotentials (conductors) different from an interconnection support. To conduct this test, the conductive strip 230-2 passing above the range C43 is brought to the voltage Vn while conductive strips 230-6, 230-7, wholly or partly above the range. C44, are brought to the voltage Vp. A first firing of ultraviolet light is performed above the C43, C44 ranges to bring them respectively to the voltage Vn and the voltage Vp. After a lapse of time, the band 230-2 conductor is brought to the potential Vp, an ultraviolet light is fired above the C43 range and is accompanied by a count of the amount of electricity supplied by the VGENl generator, to determine, as indicated above if the range C43 is still at potential Vn or not.

It will be clear to those skilled in the art that the present invention is capable of various other alternative embodiments, particularly as regards the shape of the separator plate, its applications, the implementation of continuity tests or isolation, the realization of the discharge or collection plate, the realization of the control means, acquisition and measurement described above, and the choice of test voltages Vp, Vn.

The metal layers opening into the orifices of the separating plate to form sorts of conductive rings making it possible to regulate the flow of electrons are capable of various alternative embodiments, in particular not being layers per se, but a mesh of conductors forming after piercing the separator plate conductive areas that open at certain points of the walls of the orifices and allow to impose the desired electric field.

The separating plate according to the invention can also be used for the implementation of test methods comprising only the electron ejection by photoelectric effect, the injection then being carried out with nail beds, pointed cards. , gas discharge microtips, anisotropically conductive elastomeric layers, etc. In this case, the discharge or collection plate is used only as a collection plate. Conversely, the collection of electrons can be done with contact means such as those just mentioned and the discharge or collection plate can then be used as a discharge plate only.

The discharge or collection electrodes may have various other shapes than those described above, in particular a round, triangular shape or any parallelogram shape, may be arranged obliquely relative to the surface of the the support plate, have a relief shape suitable for testing certain components, etc.

The present invention is also susceptible of various applications and is not limited to testing interconnect media. The invention makes it possible, in particular, to test or measure printed circuits equipped with components, passive and active electrical and electronic components, component terminals, etc. The invention also allows the so-called "in situ" test, ie the measurement of electronic components mounted on an interconnection support and forming electronic circuits (the target areas being either the terminals of the components themselves or tracks or beaches connected to these terminals). The invention also makes it possible to test the conductors present in the silicon integrated circuits, by firing on input / output contacts connected by equipotentials, the test of the conductors present on flat screens, and, in general, the test. any driver or component offering externally accessible test points. In such applications, the separating plate according to the invention may have, facing the elements to be tested, a raised relief face of complex shape adapted to the topography of the surface of the circuit to be tested.

Claims

KEVEM) ications

A method for injecting electrons into an electrical element (10, 11A, 11B, C43, C44) or ejecting electrons present in the electrical element, comprising the steps of: - arranging near the element at least one electron discharge electrode (22) or an electron collection electrode (22),

- bring the electrode (22) to a first electrical potential (Vh,

Vp), and - apply a particle beam (B1, BI1, B12) to the electrode or element, so that electrons are torn from the electrode or element and reach the element or the element. electrode, characterized in that the electrons circulating between the electrode and the element, or between the element and the electrode, are channeled by an electrically insulating material arranged around an electron circulation zone.

2. The method of claim 1, wherein the electrons circulate in an orifice (31, 31 ', 3IA, 31B) formed in an electrically insulating separator plate (30).

3. The method of claim 2, wherein the separator plate comprises at least one metal region (310, 311, 312) opening into the orifice (31, 31 ', 31A, 31B), and wherein the metal region is worn. at an electric potential (Vec).

4. The method of claim 3, wherein the metal region is a metal layer (310, 311, 312) pierced with the orifice (31, 31 ', 31A, 31B), forming a kind of metal ring on the walls. of the orifice.

5. Method according to one of claims 1 to 4, for the injection of electrons into the element (10, 11A, 11B, C43, C44), comprising applying to the electrode (22) a reflected particle beam (ER) from the incident particle beam (B1, BI1, B12) applied to and reflective of the element.

6. Method according to one of claims 1 to 5, wherein the particle beam is a beam of ultraviolet light.

7. Method according to one of claims 1 to 6, wherein the electric element is a conductive track, a range of a conductive track, an electrical or electronic component or a terminal of an electrical or electronic component.

8. A method for testing or measuring electrical elements (10, 11A, 11B, C43, C44) comprising electron injection steps in elements to be tested or for ejection of electrons present in elements to be tested. , by means of at least one particle beam (B1, BI1, B12) and an electron discharge or collection plate (20, 200) arranged above the elements to be tested and having electrodes (22). , 230-i), characterized in that an electrically insulating separator plate (30) is arranged between the discharge or collecting plate (20, 200) and the elements to be tested, and comprises orifices (31, 31 ', 3IA, 31B) at locations corresponding to injection or electron collection points.

The method of claim 8, wherein the separator plate (30) comprises at least one metal region (310,

311, 312) opening into orifices (31, 31 ', 31A ₇ 31B), and wherein the metal region is brought to an electric potential (Vec).

The method of claim 9, wherein the metal region is a metal layer (310, 311, 312) pierced with the orifice (31, 31 ', 31A, 31B) forming a kind of metal ring on the walls of the orifice.

The method according to one of claims 8 to 10, wherein the discharge or collection plate (20, 200) comprises electrodes (22, 220-i) of the same structure, each of which can form a discharge electrode or a collection electrode.

12. Method according to one of claims 8 to 11, wherein the discharge plate or electron collection comprises electrodes arranged in a matrix manner, in rows and columns.

13. Method according to one of claims 8 to 11, wherein the discharge plate or collection comprises electrodes in the form of conductive strips (230-i) parallel to each other.

The method according to one of claims 8 to 13, wherein an electrical element is at least one of: an electrical conductor, an electrical component, an electronic component, a terminal of an electrical conductor or a terminal an electrical or electronic component.

15. A method of manufacturing an interconnection support or an electronic circuit arranged on an interconnection support, the interconnection support or the electronic circuit comprising electrical elements, characterized in that it comprises a step of test or measurement or all of the electrical components of the interconnect ^the support or of the electronic circuit implemented in accordance with the test or measurement method according to one of claims 8 to 14.

16. A device (40) for testing or measuring electrical elements (10, 11A, 11B, C43, C44) comprising:

at least one source (S1, S2) of a particle beam (B1, BI1, B12), at least one electron discharge or collection plate (20, 200) having electrodes (22, 230-i) that can be individually carried to electrical potentials (Vp, Vn) for injecting electrons into elements or collecting electrons ejected from the elements, characterized in that it comprises a separating plate

(30) electrically insulating disposed or arranged between the discharge or collection plate (20, 200) and the elements to be tested, the separator plate comprising orifices (31, 31 ', 3IA, 31B) at locations corresponding to electron injection points in the elements or at ejection points of electrons present in the elements and forming electron circulation corridors.

17. Device according to claim 16, wherein the separator plate comprises at least one metal region (310, 311, 312) opening into the orifice (31, 31 ', 31A, 31B).

The device of claim 17 including a potential source for applying to the metal region (310,

311, 312) an electric potential (Vec).

19. Device according to one of claims 17 and 18, wherein the metal region is a metal layer (310, 311, 312) pierced with the orifice (31, 31 ', 31A, 31B), forming a kind of metal ring on the walls of the orifice

20. Device according to one of claims 16 to 19, arranged to apply to an electrode (22) a reflected particle beam (BR) from the incident particle beam (B1) applied to an element and reflected thereon , for the ejection of electrons from the electrode and their injection into the element.

21. Device according to one of claims 16 to 20, wherein the plate (20, 200) for discharging or collecting electrons comprises electrodes (22, 230-i) of the same structure, each capable of forming a discharge electrode or a collection electrode.

22. Device according to one of claims 16 to 21, wherein the plate (20, 200) discharge or collection comprises the conductive areas arranged in a matrix manner, in rows and columns.

23. Device according to one of claims 16 to 21, wherein the plate (200) for discharging or collecting electron has conductive zones (230-i) in the form of strips parallel to each other.

24. Device according to one of claims 16 to 23, wherein the particle beam is a beam of ultraviolet light.

25. Device according to one of claims 16 to 24, wherein an electrical element is at least one of the following elements: an electrical conductor, an electrical component, an electronic component, a terminal of an electrical conductor or a terminal an electrical or electronic component.