JP2003168854A - Excessively fine general purpose electrical inspection head - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an excessively fine general purpose electrical inspection head enabling to inspect an excessively fine article than before, suppressing a running cost low and realizing higher inspection stability. <P>SOLUTION: The general purpose inspection head for inspecting electrical defects of wiring of a printed wiring board and substrates for various kinds of semiconductor packages is composed of unit cells two-dimensionally arrayed in a grid shape at a prescribed interval in a semiconductor by a silicon process. The unit cell is provided with a sensor electrode, and a storage electrode, a shift electrode, and a transfer electrode for successively storing and transferring electric charges fetched to a depletion layer formed in the semiconductor to be a base by a voltage applied to the wiring and the electrode of a body to be inspected. <P>COPYRIGHT: (C)2003,JPO

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to printed wiring boards and substrates for various semiconductor packages (TAB, BGA, CS).
P etc.) and a general-purpose electrical inspection head used for electrical inspection and a method of manufacturing the same. 2. Description of the Related Art Electrical inspection jigs for printed wiring boards and substrates for various semiconductor packages (TAB, BGA, CSP, etc.) include those using a spring probe and those using a rigid probe. Printed wiring boards and substrates for various semiconductor packages are becoming finer, and products having a minimum electrode pad pitch of 100 μm or less have appeared. However, since the conventional electric inspection jig has a minimum pitch between probes of about 150 μm, it cannot keep up with high definition products. One of the reasons is that the conventional probe must be thicker than a certain level in structure. In a probe of an electric inspection jig, a contact load is generated by imparting elasticity to the probe itself so as to correspond to the height of an electrode pad of an object to be inspected which is not always the same height. The spring probe has a spring for providing elasticity, and therefore the outer diameter of the entire probe increases. 2 diameters at present
The mainstream is about 100 to 500 μm, and especially about 100 μm for high definition. Further, in the rigid probe, the probe itself obtains elasticity by bending. In order to obtain the required load and to realize the appropriate bending that returns to the original state when the load is removed, the metal wire used as the probe must have a certain thickness or more.
At present, the thinnest one having a diameter of about 70 to 150 μm is manufactured. [0004] The conventional type of probe has such a limit in thickness, and therefore cannot respond to higher definition than the current state. Also, it is virtually impossible to produce a general-purpose inspection head with the conventional probe due to the limit of the minimum inter-probe pitch, and a jig must be produced for each product, leading to an increase in running costs. . Furthermore, the conventional probe has a problem of poor contact, and if the load of the probe is increased for the purpose of avoiding the problem, there is a problem that a dent is formed on the electrode pad of the inspection object. . SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems in an electric inspection jig for a printed wiring board and various semiconductor package substrates, and has a higher definition than before. It is an object of the present invention to provide a high-definition general-purpose electric inspection head that enables inspection of the same, keeps running costs low, and realizes higher inspection stability. [0007] In order to solve the above-mentioned problems in the present invention, a general-purpose inspection head for inspecting electrical defects in wiring of a printed wiring board and various semiconductor package substrates is provided. A plurality of unit cells arranged two-dimensionally in a lattice at predetermined intervals in a semiconductor by a semiconductor manufacturing (silicon) process. The unit cells are based on sensor electrodes, wiring of a device under test, and voltages applied to the electrodes. A high-definition general-purpose electrical inspection head characterized by being provided with a storage electrode, a shift electrode and a transfer electrode for sequentially storing and transferring electric charges taken into a depletion layer formed in a semiconductor to be formed. Things. [0008] Embodiments of the present invention will be described below with reference to the drawings. FIG. 1A is a schematic plan view showing a high-definition general-purpose electric inspection head of the present invention, and FIG.
1 shows schematic sectional views of unit cells constituting a high-definition general-purpose electric inspection head. The high-definition general-purpose electric inspection head 100 of the present invention has unit cells 10 two-dimensionally arranged in a lattice as shown in FIG. 1A, and the unit cell 10 is a probe 1 in a conventional inspection jig.
Equivalent to a book. The unit cell 10 includes an insulating layer 2, a sensor electrode 3, a shield electrode 4, a storage electrode 5, a shift electrode 6, a transfer electrode 7 and a supplementary electrode 8 formed on a silicon 1 by using a semiconductor manufacturing (silicon) process. As formed, silicon 1 is obtained by adding trivalent impurities (for example, indium) and pentavalent impurities (for example, phosphorus) to Si, and has two kinds of charges of holes and electrons. The insulating layer 2 is mainly made of SiO ₂
Is used. The sensor electrode 3 is an electrode for taking in a voltage from an electrode of the device under test and a wiring pattern. The shield electrode 4 is for shielding a voltage from an electrode of the device under test and a wiring pattern on a portion other than the sensor electrode portion, and an aluminum electrode is used. The storage electrode 5, the shift electrode 6, and the transfer electrode 7 are electrodes for forming a depletion layer in the semiconductor of silicon 1 and sequentially storing and transferring the captured charges. The replenishing electrode 8 is an electrode for replenishing charges reduced as carriers. FIG.
The method and procedure for manufacturing the head and unit cell shown in FIGS. 9A and 9B are exactly the same as those for manufacturing a general CCD (charge coupled device). FIGS. 2 to 9 show the operation of each unit of the unit cell when the electrode pad 21 of the device under test 20 is inspected using the high-definition general-purpose electric inspection head of the present invention. Although the sizes of the sensor electrode 3 and the electrode pad 21 are substantially the same for convenience of explanation, the size of the electrode pad 21 is actually about 10 μm even at the smallest, and the size of the unit cell of the inspection head is about 3 μm. Therefore, it can be used as a general-purpose inspection head. FIG. 2 shows a state in which no inspection is performed, and a negative voltage is applied to the sensor electrode 3 in advance. This is to prevent extra electrons from being transferred as carriers even when the electrode pad 21 of the device under test 20 is not on the sensor electrode 3. FIGS. 3 to 9 show the unit cell 10 at the time of inspection.
The function of each part will be described. First, the high-definition general-purpose electric inspection head 100 of the present invention is brought sufficiently close to the inspection object 20. When a positive voltage is applied to the electrode pad 21 of the device under test 20, a depletion layer 11 is generated in a portion located below the sensor electrode 3 in the silicon 1 with respect to holes, and electrons in the silicon 1 are depleted. It is taken into the layer 11 as a carrier 12 (see FIG. 3). Here, the shield electrode 4 is grounded at the time of inspection. A positive voltage is applied to the storage electrode 5 to generate a depletion layer deeper than the depletion layer 11 formed below the sensor electrode 3. Electron 1 as carrier
2 moves from the depletion layer 11 below the sensor electrode 3 to the depletion layer 11a below the storage electrode 5 (see FIG. 4). The positive voltage applied to the electrode pad 21 of the device under test 20 is cut off. Depletion layer 1 under sensor electrode 3
1 disappears, and the electrons 12 as carriers are stored in the depletion layer 11a below the storage electrode 5 (see FIG. 5). A positive voltage larger than that of the storage electrode 5 is applied to the shift electrode 6. The electrons 12 serving as carriers move from the depletion layer 11 a under the storage electrode 5 to the depletion layer 1 under the shift electrode 6.
1b (see FIG. 6). The positive voltage of the storage electrode 5 is turned off. The depletion layer 11a under the storage electrode 5 disappears, and the electrons 12 as carriers are stored in the depletion layer 11b under the shift electrode 6 (see FIG. 7). A positive voltage larger than that of the shift electrode 6 is applied to the transfer electrode 7. The electrons 12 serving as carriers move from the depletion layer 11b under the shift electrode 6 to the depletion layer 1 under the transfer electrode 7.
1c (see FIG. 8). The positive voltage of the shift electrode 6 is turned off. The depletion layer 11b under the shift electrode 6 disappears, and the electrons 12 as carriers are accumulated in the depletion layer 11c under the transfer electrode 7 (see FIG. 9). Thereafter, the electrons 12 as carriers are sequentially transferred by a transfer electrode (not shown). Electrons 12 which are carriers reduced by being taken in the depletion layer and sequentially transferred are replenished from the replenishing electrode 8 as appropriate. Also, the electrons existing in the silicon 1 exist naturally even in the portion located below the sensor electrode 3. If a negative voltage is not applied to the sensor electrode 3 while the inspection is being performed, even if the electrode pad 21 of the device under test 20 is not on the sensor electrode 3,
These electrons are transferred together as carriers and the S / N ratio is reduced (see FIG. 10). By applying a negative voltage to the sensor electrode 3, electrons do not approach below the sensor electrode 3, and when there is no electrode pad 21 of the device under test 20 on the sensor electrode 3, extra electrons are generated. Can be prevented, and the S / N ratio can be improved (see FIG. 11). In the above description of the structure and operation of each part, the same applies even if the terms “electrons” and “holes” and “positive voltages” and “minus voltages” are replaced. The high-definition general-purpose electrical inspection head of the present invention is manufactured by manufacturing the head itself by a silicon process and performing electrical inspection of a printed wiring board and various semiconductor package substrates by using a charge transfer technique. Therefore, it is possible to cope with a higher definition product than the conventional inspection jig, and it is possible to keep running costs low. Furthermore, in the field of electrical inspection of printed wiring boards and various semiconductor package substrates, there is a practical effect that a high-definition general-purpose electrical inspection head having high inspection stability can be provided.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 (a) is a schematic plan view showing an example of a high-definition general-purpose electrical inspection head of the present invention. (B) is a schematic sectional view of a unit cell constituting the high-definition general-purpose electric inspection head of the present invention. FIG. 2 is an explanatory diagram showing the operation of each unit of a unit cell when an object to be inspected is inspected using the high-definition general-purpose electric inspection head of the present invention. FIG. 3 is an explanatory diagram showing the operation of each unit of a unit cell when an object to be inspected is inspected using the high-definition general-purpose electric inspection head of the present invention. FIG. 4 is an explanatory diagram showing the operation of each unit of the unit cell when inspecting an object to be inspected using the high-definition general-purpose electric inspection head of the present invention. FIG. 5 is an explanatory diagram showing the operation of each unit of the unit cell when inspecting an object to be inspected using the high-definition general-purpose electric inspection head of the present invention. FIG. 6 is an explanatory diagram showing the operation of each unit of the unit cell when inspecting an object to be inspected using the high-definition general-purpose electric inspection head of the present invention. FIG. 7 is an explanatory diagram showing the operation of each unit of the unit cell when inspecting an object to be inspected using the high-definition general-purpose electric inspection head of the present invention. FIG. 8 is an explanatory diagram showing the function of each unit of the unit cell when inspecting an object to be inspected using the high-definition general-purpose electric inspection head of the present invention. FIG. 9 is an explanatory diagram showing the operation of each unit of the unit cell when inspecting an object to be inspected using the high-definition general-purpose electric inspection head of the present invention. FIG. 10 is an explanatory diagram showing the function of each unit of the unit cell when inspecting an object to be inspected using the high-definition general-purpose electric inspection head of the present invention. FIG. 11 is an explanatory diagram showing the operation of each unit of a unit cell when an object to be inspected is inspected using the high-definition general-purpose electric inspection head of the present invention. [Description of Signs] 1 ... Silicon 2 ... Insulating layer 3 ... Sensor electrode 4 ... Shield electrode 5 ... Storage electrode 6 ... Shift electrode 7 ... Transfer electrode 8 ... Replenishment electrode 10 ... Unit cell 11 .., 11a, 11b, 11c... Depletion layer 12... Electrons (carriers) 20.

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Claims (1)

Claims 1. A general-purpose inspection head for inspecting electrical defects of wiring of a printed wiring board and various semiconductor package substrates, wherein the inspection head is formed in a semiconductor at a predetermined interval by a semiconductor manufacturing process. The unit cells sequentially accumulate electric charges taken into a sensor electrode and a depletion layer formed in a base semiconductor by a voltage applied to a wiring and an electrode of a device under test. A high-definition general-purpose electrical inspection head, comprising: a storage electrode for transferring data; a shift electrode; and a transfer electrode.