JP2007064645A - Semi-conductor inspection method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To effectively shorten the inspection time without rising the cost of an inspection device at the inspection of electric performance of terminal group. <P>SOLUTION: The inspection is performed as follows: (step 1) the total sum of the leak current of each terminal of the terminal group (total sum of the leak current Is) are measured en block; (step S2) the total leak current Is is compared with the specific standard value per one terminal and finished after determination of acceptance if passed the inspection, or transfers to the next step if failed; (step S3) whether the failed terminal group is possible to group separate or not is determined, and the inspection is finished by determining unacceptable if the group separation is impossible because of one terminal, but if the group separation is possible, transferred to the next step; (step S4) the failed terminal group is group separated, the total sum current Is is detected for every group; and (step S5) the total leak current Is is compared with the specific standard value and determined that the inspection is accepted if pass the inspection, but if failed transferred to step S3. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a semiconductor inspection method for inspecting electrical characteristics of a semiconductor element (IC), and more particularly to a semiconductor inspection method for inspecting direct current (DC) characteristics of a terminal group.

An IC manufactured by a manufacturer is inspected for electrical characteristics such as DC characteristics and function characteristics by a so-called IC tester. The IC tester includes a DC measurement unit that enables measurement of DC characteristics. For example, in order to measure a leakage current (input leakage current) of an input terminal of a MOS IC, the DC measurement unit is a terminal to be inspected. , A voltage of VDD (power supply) level or GND (ground) level is applied from the DC measurement unit, and a leak current is measured with an ammeter in the DC measurement unit (see, for example, Patent Document 1).
JP 05-256907 A

  In general, the number of DC measurement units mounted on an IC tester is less than the total number of terminals to be inspected. The reason is that the mounting of a large number of DC measurement units makes the IC tester very expensive and very large. In order to inspect the DC characteristics of IC terminals with an IC tester in which the number of DC measurement units is limited in this way, the terminal groups to be inspected are grouped into the number of DC measurement units, and the terminal groups of each group are grouped. One terminal must be measured, and the length of the inspection time is a problem.

  The present invention has been made in view of the above problems, and provides a semiconductor inspection method capable of efficiently reducing the inspection time without increasing the cost of the inspection apparatus in the DC characteristic inspection of the terminal group. Objective.

  In order to achieve the above object, a semiconductor inspection method of the present invention is a semiconductor inspection method for inspecting DC characteristics of a terminal group of semiconductor elements, and collectively measuring the terminal group to obtain a total amount of characteristic values of each terminal. A first step to compare with the standard value per terminal for the total amount acquired in the first step, the test is passed if it passes, and the second step is transferred to the next step if it fails Determining whether it is possible to group the terminal group that failed in the step and the second step, and when the terminal group consists of one terminal and grouping is impossible, the test is terminated as a failure. When grouping is possible, the third step to be shifted to the next step and the terminal group that has failed in the second step are grouped, and each group is grouped. 4th step of measuring and acquiring the total amount of characteristic values of each terminal, and comparing and determining the total amount of each group obtained in the 4th step with the standard value per terminal, It ends with a test pass, and when it fails, it comprises a fifth step that shifts to the third step.

  The terminal group is preferably composed of a plurality of input terminals, and the DC characteristic is preferably a leakage current. Further, it is preferable that the terminal group includes power supply terminals of a plurality of semiconductor elements, and the direct current characteristic is a leakage current.

  According to the present invention, it is possible to make a pass / fail determination without measuring each terminal group one by one, and therefore, the inspection time can be efficiently shortened without providing a large number of expensive DC measurement units that increase the cost of the inspection apparatus. be able to.

  In FIG. 1, an IC tester 10 includes a control circuit 11 that controls each part, a relay circuit 12 connected to the IC 2, a DC measurement unit 13 connected to the relay circuit 12, and an input / output connected to the control circuit 11. Part 14. The IC 2 to be inspected is, for example, a packaged MOS semiconductor memory element, and includes external terminals such as a power supply terminal, an input terminal, an output terminal, and a control terminal.

  The relay circuit 12 includes a plurality of switches 15 connected to the terminal group of the IC 2, and each switch 15 opens and closes independently based on the control of the control circuit 11. The DC measurement unit 13 includes a power supply 16 having a variable voltage value, and an ammeter 17 connected between the power supply 16 and the relay circuit 12, and is controlled via the relay circuit 12 based on the control of the control circuit 11. A predetermined voltage is applied to the terminal group of the connected IC 2 and the leakage current flowing out from the terminal group is measured.

  The input / output unit 14 includes a keyboard, a display, a file input / output device, and the like, and inputs / outputs various data to / from the control circuit 11. A test program is input to the control circuit 11 via the input / output unit 14, and the control circuit 11 controls each unit based on the test program. Further, the control circuit 11 outputs the inspection result to the outside via the input / output unit 14.

  For example, as shown in FIG. 2, the input terminal of the IC 2 is connected to an internal circuit 26 via a protection circuit 22 composed of two diodes 20 and a resistor 21 and an inverter 25 composed of a PMOS transistor 23 and an NMOS transistor 24. Has been. When a GND potential (0 V) is applied to the input terminal, a slight leakage current is generated from the VDD side of the protection circuit 22 or the inverter 25. Further, when a VDD voltage (for example, 3 V) is applied to the input terminal, a slight leakage current is generated from the protection circuit 22 or the GND side of the inverter 25. The leakage current is about several nA per input terminal when the IC 2 is normal, but the product standard value presented to the user is, for example, “500 nA or less per input terminal”. Set with a sufficient margin.

  Next, a method for inspecting the leakage current of the input terminal of the IC 2 by the IC tester 10 will be described based on the flowchart of FIG. The inspection is performed on the input terminals A0 to A15 of the IC2. First, the control circuit 11 controls the relay circuit 12 to connect the DC measurement unit 13 to the terminal group (A0 to A15) to be inspected, and also controls the DC measurement unit 13 to apply the VDD voltage or the voltage to the terminal group. A GND potential is applied, the terminal group is collectively measured, and the total amount of leakage current (total leakage current Is) of each terminal is detected (step S1).

  Next, the control circuit 11 determines whether or not the detected total leakage current Is satisfies a standard value per terminal (for example, 500 nA) (step S2). If the total leakage current Is is equal to or less than the standard value (Yes determination, pass), the inspection is terminated with the IC 2 to be inspected as acceptable. On the other hand, when the total leakage current Is is larger than the standard value (No determination, fail), it is determined whether the failed terminal group can be grouped, that is, includes a plurality of terminals (step S3). In the first flow, since the terminal group determined in step S2 is 16 terminals A0 to A15, when failing in step S2, grouping is naturally possible.

  Next, the control circuit 11 controls the relay circuit 12 to group the terminals that failed in step S2 (for example, into two groups of terminals A0 to A7 and terminals A8 to A15), and DC measurement. The unit 13 is controlled to measure each group at once, and the total leakage current Is is detected for each group (step S4).

  The control circuit 11 determines whether or not the detected total leakage current Is of each group satisfies the standard value per one terminal (step S5). When the total leakage current Is of each group is equal to or less than the standard value (Yes determination, pass), the inspection is terminated with the IC 2 to be inspected as passing. On the other hand, when the total leakage current Is of at least one group is larger than the standard value (No determination, fail), the process proceeds to step S3 to determine whether the terminal group of the failed group can be further grouped. To do.

  If grouping is possible (Yes determination), the same steps as described above are repeated after step S4. On the other hand, when grouping is impossible, that is, when the terminal group is composed of one terminal (No determination), the IC2 to be inspected is rejected and the inspection is terminated.

  In the above inspection method, the terminal groups to be inspected are collectively measured to determine whether or not the total leakage current satisfies the standard value per terminal. If a failure occurs, the failed terminal groups are grouped again. Measurement is performed, and the pass / fail of the inspection is determined by repeating the grouping until each group passes the determination or the failed group becomes one terminal and cannot be grouped. As a result, the pass / fail determination can be performed without measuring the terminal group one by one, and the inspection time is shortened.

  In the above embodiment, only one DC measurement unit 13 is provided in the IC tester 10, but the present invention is not limited to this, and a plurality of DC measurement units 13 may be provided. For example, the DC measurement unit 13 may be assigned to each group grouped in step S4, and the total leakage current Is of each group may be detected simultaneously. The number of groups to be grouped in step S4 is not limited to 2 and may be 3 or more.

  In the above embodiment, the case where the leakage current of the input terminal is inspected has been described as an example. However, the present invention is not limited to this and can be applied to other DC characteristics inspection. For example, the present invention can be applied to the inspection of a leakage current of a power supply terminal (power supply leakage current). As shown in FIG. 4, the power supply leakage current is inspected simultaneously for a plurality of ICs 2 in a short time by connecting the power terminals of the plurality of ICs 2 in parallel to the relay circuit 12 and performing the above inspection method. Can do.

  In the above embodiment, the IC 2 is a MOS type semiconductor memory element, but the present invention is not limited to this, and can be applied to other semiconductor elements such as a logic IC and an image sensor. Further, the IC 2 is not limited to a packaged one, and may be in a wafer state.

  The IC 2 is connected to the IC tester 10 via a test board (not shown). The relay circuit 12 shown in the above embodiment may be provided on a test board. The test board corresponds to a performance board on which an IC socket is mounted when the IC 2 is in a package state, and corresponds to a probe card attached to the prober when the IC 2 is in a wafer state.

It is a block diagram which shows the electrical structure of IC tester. It is a circuit diagram which shows the circuit connected to the back | latter stage of the input terminal. It is a flowchart explaining the inspection method of an input leakage current. It is a block diagram in the case of inspecting simultaneously the power supply leakage current of multiple ICs.

Explanation of symbols

10 IC Tester 11 Control Circuit 12 Relay Circuit 13 DC Measurement Unit 14 Input / Output Unit 15 Switch 16 Power Supply 17 Ammeter

Claims (3)

In a semiconductor inspection method for inspecting direct current characteristics for a terminal group of semiconductor elements,
A first step of collectively measuring the terminal group to obtain a total amount of characteristic values of each terminal;
A second step of comparing and determining the total amount acquired in the first step with a standard value per terminal, ending as an inspection pass if passed, and moving to the next step if failed;
It is determined whether or not the terminal group that has failed in the second step can be grouped. When the terminal group is composed of one terminal and grouping is impossible, the test is terminated as a test failure. A third step to move to the next step if possible;
A fourth step of grouping the terminal groups that have failed in the second step, and collectively measuring each group to obtain a total amount of characteristic values of each terminal;
The total amount of each group obtained in the fourth step is compared with the standard value per one terminal, and if passed, the test is passed as a pass, and if failed, the process proceeds to the third step. Steps,
A semiconductor inspection method comprising:   The semiconductor inspection method according to claim 1, wherein the terminal group includes a plurality of input terminals, and the DC characteristic is a leakage current. The semiconductor inspection method according to claim 1, wherein the terminal group includes power supply terminals of a plurality of semiconductor elements, and the DC characteristic is a leakage current.

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