FR2882824A1 - PROBE CARD - Google Patents

Abstract

The present invention provides a probe card comprising: - a substrate (10); - a support dielectric material disposed in the substrate (10); - an external connection terminal (1) placed on the support dielectric material; and a conductive layer (3,4) disposed between and substantially in contact with both the substrate (10) and the dielectric support material at the sides and bottom of the dielectric material, having mesh portions or cut parts.

Description

PROBE CARD

  The present invention relates to a probe board for connection to a board to be measured with a measuring device in a semiconductor wafer test device.

  Significant progress has been made in recent semiconductor manufacturing technology, including the advancement of fine processing technology required for high density integration. For a high density implementation as well as for the suppression of heat generation and the reduction of each element, the current and voltage required for operation in semiconductor devices are reduced from year to year . Thus, the importance of microcurrent measurement has been recognized and higher accuracies in microcurrent measurement are required in probe cards for connecting measuring devices and wafers.

  Such a requirement is also present in the wafer processing control test. As a conventional test method for process control, measurement chips called TEG (Test Element Group) are formed at the same time that ordinary chips are formed on the wafers for feature measurement purposes. . In such measurements, a probe card is used as an interface card between a measuring device and a wafer probe device for moving and positioning a wafer to be measured, and is provided around its circular hole. a plurality of wafer contact needles also referred to as contact blades so as to make contact with the wafer measurement terminals.

  In FIG. 10, a probe card is generally a circular disc 100 having a diameter of about 20 to 30 cm, with its central portion provided with an opening 102 through which the contact pins or the blades (not shown) may extend for contact with measurement terminals on a semiconductor wafer placed to be measured just below the probe board. Each wire 103 extends from each needle or blade positioned at its inner periphery to the outer periphery where it is connected to a measuring device or the like. That is, a signal taken from each terminal of a semiconductor wafer to be measured is introduced into the outer periphery of the probe board through each needle or blade and is then sent to a measuring device from an external connection terminal 104 positioned on the outer periphery of the probe board. At this time, the wires for connection of the semiconductor wafer to be measured to the measuring device are a few tens and are mutually adjacent. Guard patterns 105 formed with a conductor are positioned around the corresponding external connection terminals 104. In the example shown in the drawings, the number of terminals or external connection pins is forty-eight (48). Such a probe card is also known as a personality card or interface card. See Japanese Utility Model (JP-A) n Showa 64-47042 Provisional Publication and Japanese Patent Publication (JP-A) No. Heisei 8-330369.

  In general, such a probe board has external contact terminals 104 at its outer periphery for connection to a measuring device. Each contact terminal 104 is composed of a plane conductor disposed on a surface of a substrate of a probe board on which, for example, a conductive contact needle, such as a contact pin element which comprises a conductive rod with a circular cross section provided with a spring at its base and surrounded by a cylindrical member so that upon application of the appropriate force, the rod is retracted and biased by a reaction force so as to establish the electrical contact by pushing the tip of the rod against a surface of the conductor, with a mechanism to ensure safe electrical contact is pushed against the flat conductive surface of the probe board for connection thereby to an external device, such as that a device for me-sure. In addition, each external contact terminal 104 has a pattern extension portion 106 near its inner periphery, and a corresponding planar conductor on the surface of the probe board extends inwardly. At the pattern extending portion, one end of a coaxial cable 103 is connected and the other end of the coaxial cable is connected to a base end of a needle which is in the shape of a needle or a blade as described above. That is, the coaxial cable 103 extends into the air between the pattern extension portion and the contact needle. The needle or blade is attached to the inner periphery of the sound card and extends therefrom inwardly. In addition, the tip of the inwardly extending needle or blade is connected to a predetermined terminal on a semiconductor wafer to be tested.

  As previously mentioned, in the field of semiconductor element testing, test devices that can measure microcurrents smaller than the usual level are needed. Similarly, the measurement accuracy of the femtoampere order is required for the interface boards used for the wafer test devices. Major problems with the development of test devices with such high performance include the leakage current between adjacent electrical wires for connection of a test device and a semiconductor to be measured and the dielectric absorption of producing between these wires and the dielectrics in a substrate of the probe board.

  By way of example, the problem of dielectric absorption occurs due to the dielectric absorption properties (absorption current) of the dielectric used as the substrate of the probe board. In general, the insulating materials exhibit a dielectric bias when a voltage applied across two electrodes changes and gradually absorbs a current until the polarization process is completed. Accordingly, even if a predetermined voltage is applied to a semiconductor wafer for current measurement, the current measurement can not be performed correctly for a certain time and a waiting time is necessary until that the circulation of the current becomes stabilized. Waiting time is also necessary when the power supply is stopped because a discharge current flows progressively. For conventional interface boards, for wafer measuring devices, it is not unusual that such a waiting time of the measurement can last a few tens of seconds until the current of dielectric absorption is reduced by the order of the femtoampere. This is one of the important problems in the case of reducing the time required for the measurement of microcurrent.

  Since the measurement accuracy of the femtoampere order is now required, the leakage current flowing in a dielectric material between two adjacent wires has also become important.

  Of the components on the probe board as previously mentioned, the portions of the external contact terminal and the pattern extension portion tend to be influenced by dielectric absorption and current leakage. The coaxial cable extending from each pattern extension portion is in the air so that it is little influenced by dielectric absorption or current leakage. As a needle part, for example, a highly insulating coaxial needle may be used and a sheathing wire surrounding the core wire of this needle may be connected to a guard. In addition, the isolation between adjoining needles having a portion of the uncoated needle thread with the shielding wire is good because it is obtained by air having the same dielectric constant approximately as that emptiness. Likewise, the response time of the dielectric bias is not a problem.

  In order to take into account these problems caused by the external contact terminal, conventionally a plurality of through holes are formed from the electrodes on the surface through the substrate of the probe board so that the periphery of the electrodes can be defined. An example of one of these technologies is described in Japanese Patent Provisional Publication No. 8-335754.

  A problem in such a process is that deformation tends to occur in the probe board as the number of through holes is increased and the physical strength of the board deteriorates in or near the hole region. through. Even though the number of through holes is increased without regard to manufacturing difficulties and cost increases, a certain leakage current through the dielectric between these through holes still remains a problem and a dielectric loss can not be reduced at a desired level as a higher level of measurement accuracy is required.

  It should be noted that there are variations in the dielectric properties and leakage current of each wire for each probe board. Accordingly, even if the control of the manufacturing process is sufficiently improved, such variations in the dielectric and current leakage properties of each wire for each probe board should limit the accuracy of the current measurements. For example, in the case of a probe board currently used with 48 pins, after applying a voltage of about 10 volts, the leakage current 10 seconds after this voltage application on most pins is approximately However, such a leakage current of other specific pins is approximately 1 to 2 x 10-13 A. It is an object of the present invention to reduce the waiting time of the measurement which results from the dielectric absorption and to reduce the leakage current under normal conditions so as to improve the accuracy of the measurement of microcurrents or fluctuations thereof. It is another object of the present invention to reduce variations in the properties of each pin or probe board.

  In view of the above-described problems of the prior art, the present invention relates to a structure in which an external connection terminal for use in a probe card is surrounded by conductors.

  The present invention provides a probe board comprising a substrate, a support dielectric material disposed in the substrate, an external connection terminal placed on the support dielectric material, a conductive layer disposed between and substantially in contact with the substrate. both the substrate, the bottom part and the sides of the dielectric support material, characterized in that said conductive layer comprises mesh parts or cut parts.

  Advantageously, the probe card has at least one of the following characteristics: the conductor comprises at least one lower conductor disposed on a bottom of a recess formed in the substrate for receiving the dielectric support material and a lateral conductor disposed on the faces side of the recess and a gap or gap is disposed between said dielectric support material and the lateral conductor; the air gap or space is sealed by a dielectric material from outside the substrate; the probe card comprises two or more external connection terminals and the electrical connection between these external connection terminals is ensured by the electrical connection disposed inside the substrate; said conductor comprises mesh parts or cut parts; said external terminal is placed at a lower level for a predetermined distance than the surface of the body of the substrate; said conductor is connected to a guard terminal; and, said guard terminal is provided with active guard.

  The conductors surrounding the ex-dull connection terminal in the present invention are preferably connected to a guard terminal, more preferably to an active guard terminal.

  The conductor attached to the substrate surrounds the external connection terminal in the substrate. Assuming that the conductor has a box-like configuration, the underside of the conductor is positioned below the outer terminal in the substrate and the four side faces are positioned in the substrate and surround the external connection terminal from all four sides. The term "in the substrate" does not necessarily mean that the conductor is embedded in the substrate. That is, at least a portion of each conductor should appear from the surface of the substrate and may protrude therefrom. In addition, when the surface of the substrate is recessed or notched, the conductor can be exposed in the recessed or notched portions of the substrate or exceeded in the air.

  In such a construction of the present invention, the properties of femtoampere-like microcurrent can be enhanced so that the accuracy of measurement can be improved. The waiting time that results from the instability of the current resulting from the dielectric absorption can also be reduced. In addition, the substrate may include other electrical grids that may not be included in the substrate because they may degrade microcurrent properties. Since the probe card of the present invention can be generally made of a planar structure (although three-dimensional structures can be provided), it can be easily manipulated and reduce the cost for storage or transport. In addition, the present invention is compatible with the probe cards currently found on the market.

  The substrate may have a monolayer structure but preferably has a multilayer structure. In a preferred embodiment, for example, the conductive wires may be disposed among the layers and through-holes or through-holes may be formed in a multilayer substrate by one of the currently known technologies for making multilayer substrates.

  The probe card of the present invention may be manufactured in accordance with the following procedure, although it is not limited to any manufacturing method. The external connection terminal surrounded by the conductor can be produced, for example, by forming a recess in a substrate, by disposing a box-type external connection terminal portion in which an external connection terminal is formed on the upper surface and a conductive material is disposed on the side surfaces by electrodeposition or the like and by fitting the box-type external connection terminal portion into the recess. Alternatively, the external connection terminal may be produced by forming a recess in a substrate, disposing a conductive material in the electrodeposition-recessed portion, or the like, and by fitting or adhering a dielectric member in this recess. of the box type and an external connection terminal disposed thereon. Alternatively, in the case of a multilayer substrate, the external connection terminal surrounded by the conductors may be produced by placing a conductive pattern on an inner layer positioned beneath the external connection terminal, by cutting a pattern surrounding the terminal and reaching the inner layer after lamination and applying a conductive material in the cut pattern.

  Figure 1 is a perspective view of a basic embodiment of the present invention, with substrate portions around the side and bottom conductors being removed.

  Figure 2 is a sectional view along the line A-A of Figure 1.

  Figure 3 is a sectional view corresponding to Figure 2 showing another embodiment of the present invention.

  Fig. 4 is a schematic diagram for approximately determining the capacitance between an external connection terminal and each side surface of an embodiment of the present invention.

  Fig. 5 is a perspective view of another embodiment of the present invention with the substrate portions around the side and bottom conductors being removed, as shown in Fig. 1.

  Fig. 6 is a perspective view corresponding to Fig. 5 showing yet another embodiment of the present invention.

  Fig. 7 is a perspective view showing yet another embodiment of the present invention.

  Fig. 8 is a sectional view of an embodiment in which gaps are provided within a substrate of the present invention.

  Fig. 9 is a sectional view of another embodiment in which gaps are provided within a substrate of the present invention.

  Figure 10 is a top view of a sound map showing its entire construction.

  Several embodiments of the present invention will be described with reference to Figs. 1-9. Fig. 1 shows a basic embodiment of the present invention. In the same drawing, portions surrounding the substrate are removed to show the external connection terminal 1 and a conductive material 2, 3, 4 placed around it. The conductive material 2, 3, 4 is electrically connected and these are equipotential to each other. On the substrate, the ex-dull connection terminal 1 and the upper guard pattern 2 surrounding the terminal 1 can be seen, both being composed of a conductor. On the external connection terminal 1 and on the upper guard pattern 2, three contact pin elements 20, 21, 22 protruding from a test head of a semiconductor measuring device are positioned to be in position. contact with their corresponding targets. In this embodiment, the contact pin element 20 is a so-called "force" terminal for applying a voltage and measuring a current, the contact pin element 21 is a "detection" terminal. "to take a voltage that needs to be measured. These terminals of force and detection provide a Kelvin connection. The contact pin element 22 is a guard pin for applying a voltage to the upper guard pattern 2. The guard pin member 22 acts as a guard terminal in an active guard device in which it is held equipotential to power and sense terminals for blocking external influences over the external connection terminal or in a passive guard mechanism in which it is connected to a fixed voltage. The present invention is applicable to both guard mechanisms whether they are active or passive. In FIG. 1, these terminals of force and detection are placed on the same external connection terminal 1. However, two external connection terminals can be provided separately for the detection and force terminals and each external connection terminal can be connected to a probe needle using a separate coaxial cable.

  FIG. 1 shows the external connection terminal 1 surrounded by the lateral conductors 3 and the bottom conductor 4. The lateral conductors 3 and the bottom conductor 4 are electrically connected to one another and also connected to the upper guard pattern 2. Ideally, the external connection terminal 1 is electromagnetically separated from a dielectric constituting the external substrate via the lateral conductors 3 and the bottom conductor 4. However, as will be described below, the complete electromagnetic separation is not not required for certain specific embodiments of the present invention. A core wire of the coaxial cable 8 for connection with a probe needle is connected to an external connection terminal 1 and the other external conductor of the coaxial cable 8 is connected to the conductor 2.

  Figure 2 shows a sectional view along the line A-A showing a sectional view of the substrate 10. As can be seen in Figure 2, the substrate consists of two layers. The surface of the first layer 5 defines the surface of the substrate 10 and the lower conductor 4 is disposed between the first layer 5 and the second layer 6. This structure can be manufactured by providing the conductor 4 by using electrodeposition or the like on the bottom of the first layer 5 or at the top of the second layer 6. The side conductor 3 may be formed using plating or the like on faces created by cutting off part of the first layer 5. Alternatively, the driver may be formed by electrodeposition or the like on the side and bottom faces of the dielectric 7 to fit into the cut surface in the first layer 5.

  Examples of materials that can be used to make the substrate include synthetic resins commonly used for substrates of electrical circuits, for example, glass fiber reinforced polycarbonates, polyimides, epoxy-glass resins, and other products such as ceramics. Examples of the materials used for the dielectric to be placed in the substrate 10 to support the external connection terminal 1 thereon include synthetic resins similar to those used for the substrate 10 as well as materials having excellent insulating properties. and dielectrics, such as PTFE. It is also possible to fabricate fine structures using materials other than those described above by applying manufacturing technologies to produce integrated circuits and micro-machining technologies.

  FIG. 3 represents another embodiment having a cross section different from that of FIG. 2. In this embodiment, air gaps 9 are arranged between the first layer 5 and the dielectric 7 supporting on it the connection terminal. external 1. These air gaps can greatly reduce the capacitance between the external connection terminal 1 and the conductors 3, 4. In the configuration of Figure 2, assuming that the capacitance values Cl and C3, as shown in FIG. 4 (A) between the external connection terminal 1 and the conductor 3 on its right and left sides are 10 pF, respectively, and assuming that the capacitance C2 between the terminal 1 and the ground conductor 4 is 10 pF, the total capacity becomes 30 pF as the sum of these. In the case where air gaps 9 are provided, as shown in FIG. 4 (B), the capacitance values C12 and 2882824 C32 corresponding to these air gaps 9 can be considered to be about 1 pF, respectively. Thus, for example, the capacitance Cl 'between the left side conductor 3 and the external connection terminal 1 is 0.9 pF as obtained by the following equation: Cl' = C12 * Cl / (C12 + Cl ) = 0.9 pF As a result, the total capacitance is about 11.8 pF as obtained by Cl '+ C2 + C3' (C3 'is the capacitance between the right-hand side conductor 3 and the ex-dull connection terminal 1), thereby significantly reducing the total capacity.

  In the structures shown in Figures 1 to 3, each side conductor 3 may protrude from the surface of the substrate (not specifically shown). In such a structure, when the contact pin elements 20, 21, 22 contact the surface of the substrate, these pin elements may not be seen from the outside and electromagnetic shielding may be provided between these pin contact elements. .

  FIG. 5 shows another embodiment in which the external connection terminals 31, 32 may be only in areas where the contact pin elements 20, 21 for connection to an ex-dull measuring device will be in contact with that -this. The connection between these terminals 31, 32 is provided by a conduction path 35 formed in the substrate. Terminal 33 can connect to a probe needle via a coaxial cable. In this embodiment, higher shielding properties can be obtained by forming a conductive pattern 34 which serves as an upper guard just near the periphery of the external connection terminals 31, 32, 33. Thus, the pin element contact 22 for measuring a guard potential can contact an upper shield 34.

  In addition, the connection to a probe needle via a coaxial cable 8 may be replaced by a shielded conductive path formed in the substrate.

  A partially or fully meshed portion, cut portions 41 and notched portions 42 in the side conductor 3 are shown in Figs. 6 (A) through 6 (C), respectively. The conductive path 35 within the substrate, as shown in FIG. 5, may be disposed through the cut portions 41 or the notched portions 42 from the outside of the connection terminal support structure. In another embodiment of the present invention, one of the lateral surfaces corresponding to the lateral conductors 3 of the dielectric supporting the external connection terminal 1 thereon may be open at a location covering all the surfaces including the underside with the driver. Such a structure is preferred for ease of manufacture and design flexibility.

  In Figures 1 to 3, substrates 10 with two-layer structures are shown as examples. Substrates having structures of three or more layers, however, can also be applied to the present invention and it is possible to use more complex structures using substrates with a number of layers. In a first example of these cases, it is possible to propose a structure in which the external connection terminal 1 is positioned lower than the surface of the substrate 10, as shown in FIG. 7. In FIG. the level of the external connection terminal 1 is lowered, while the lateral conductor 3 on the wall surfaces of the substrate 10 around the external connection terminal 1. exceeds it. Thus, when the contact pin elements 2882824 16 20, 21 touch the terminal 1, the lateral conductors 3 serve as electromagnetic shielding for the contact pin elements 20, 21 to prevent the dielectric absorption arising from the potential differences between them. components of the external connecting terminals and the spindle elements.

  As described with reference to FIGS. 3 and 4, by providing air gaps around the dielectric supporting the external connection terminal thereto, the capacitance between the external connection terminal and the surrounding conductor can be significantly reduced. The effects of dust fixation on air gap and moisture surfaces and the like can result in deterioration of the insulating resistance and dielectric absorption properties. To prevent such unwanted effects, air gaps or spaces can be sealed. Figures 8 and 9 show sectional views of these structures, respectively. In the structures of FIGS. 8 and 9, an external connection terminal 51 extends upwardly into the interior of the substrate 10. The external connection terminal 51 is supported by a support dielectric 52 embedded in the substrate 10 Spaces or gaps 54 are sealed by dielectric layers 53, respectively. In air gaps or sealed spaces 54, dry air or an inert gas is placed. The ex-dull connection terminal 51 is exposed on the surface of the substrate and the upper guard conductor patterns 55 are formed surrounding the exposed portion. In FIG. 8, the support dielectric 52 is in contact with the lateral and lower conductors 56, 57. In FIG. 9, the support dielectric 52 is in contact with the lower conductor 57 but is not in contact with the Lateral conductor 56. The structure as shown in Figures 8 and 9, is generally similar to the structure or principle of the shielded wires. Accordingly, by using such a structure instead of connecting via coaxial cables or shielded cables, it is also possible to connect the external connection terminal 51 with a probe needle.

  The present invention has been described with reference to a number of embodiments above. It is also possible, in specific applications, to replace the coaxial cable with a single core cable with a highly insulating coating typically represented by PTFE (Teflon () or the like which is to be used for connection to a probe needle.

  The probe board of the present invention as described above can reduce the waiting time resulting from the dielectric absorption occurring between the different electrical potentials and reduce the normal leakage current to a negligible level. In addition, since the insulating body placed between the different potentials can be protected by conductors, variations in the microcurrent properties for each probe board or each contact pin element due to the inherent nature of the insulative body or methods of Non-regular manufacturing can be prevented.

  Reference can be made to the entire disclosure of Japanese Patent Application No. 2000-36626 filed February 15, 2000 including the specification, claims, drawings and summary.

2882824 18

Claims (5)

  A probe card comprising - a substrate (10); a dielectric support material disposed in the substrate (10); an external connection terminal (1) placed on the dielectric support material; and a conductive layer (3,4) disposed between and substantially in contact with both the substrate (10) and the dielectric support material at the sides and bottom of the dielectric material, characterized in that said conductive layer (3, 4) has mesh parts or cut parts.   Probe card according to Claim 1, characterized in that the probe card has two or more external connection terminals (31, 32) and the electrical connection between these external connection terminals (31, 32) is ensured by the electrical connection disposed within the substrate (10). The probe card according to claim 1, characterized in that said external terminal is placed at a lower level for a predetermined distance than the surface of the substrate body (10). 4. Probe card according to claim 3, characterized in that said conductor is connected to a guard terminal.   5. Probe card according to claim 4, characterized in that said guard terminal is provided with an active guard.