JP2008145157A - Device tester - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To facilitate obtaining of the overall trend of shmoo data of a plurality of DUTs, and to calculate the correlation of the plurality of DUTs using various logical expressions without acquiring shmoo again. <P>SOLUTION: This device tester 100 includes a shmoo acquisition section 310 for acquiring shmoo data of the plurality of DUTs 140, a data storage section 312 for storing a plurality of acquired shmoo data in a tester memory, a data selection section 314 for making a user select one or two or more shmoo data from the plurality of shmoo data with a shmoo tool, and a preview function section 318 for arranging and displaying the one or two or more selected shmoo data on a display section 212 at once. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a device tester capable of browsing shmoo data using a shmoo tool.

  In recent years, an integrated circuit (IC: Integrated Circuit) has been increased in capacity, speed, and size (high density). In a device having such an integrated circuit, a high-speed and complicated process is required for electrical function testing as the density of the integrated circuit increases. In a device tester that performs such an electrical function test, a function test such as an access time margin is performed on a device under test (Device Under Test: hereinafter referred to as “DUT”), for example, various microcomputers and memories. ing.

  In the device tester, it is possible to perform a shmoo (see, for example, Patent Document 1) for deriving the electrical characteristics of the DUT by changing correlated test parameters such as voltage and input / output timing set in the DUT. The device tester is equipped not only with a single DUT but also with a multi-shmoo function that tests a plurality of DUTs together and independently derives the electrical characteristics of each DUT.

  The user can visually grasp the characteristics of the DUT by using a shmoo tool that graphically selects and displays the shmoo data that is the result data of the shmoo.

  FIG. 7 is an external view showing the user interface 10 of the shmoo tool. The shmoo tool is processed by the central control unit of the device tester and displays shmoo data via the user interface 10. The user interface 10 of the shmoo tool includes a display DUT box 12 for designating a DUT to be displayed, and a main area 14 that graphically represents the shmoo data of the DUT. When, for example, “3” is entered in the display DUT box 12, DUT shmoo data with “3” as the device number is displayed in the main area 14.

  In the example of FIG. 7, the shmoo tool automatically changes the voltage parameter and the timing parameter, and it is inspected whether the actual measurement value is included in the range indicated by the parameter (pass / fail). Specifically, it is investigated whether the output voltage detected after a predetermined range (STB0) 0 to 320 nsec from a predetermined input signal to the DUT is within an allowable range, particularly the upper limit (VOH) 0 to 4V of the range. . For example, in the DUT having the device number “3”, since the output of the DUT at the time of 176 nsec delay from the predetermined input signal is within the range of 0 to 3 V, the partial data 16 of STB0 = 176 nsec and VOH = 3 V is “ Pass ". Thus, the shmoo data is formed by arranging a plurality of cells as partial data in a grid pattern, and the passed partial data and the failed partial data are represented by different colors.

As an order of measurement, for example, an appropriate voltage is selected from the upper limit (VOH) of the range, and the output signal is measured by sequentially shifting STB0 in the voltage range. When the STB0 shift is completed, the upper limit (VOH) of the range is changed, and the STB0 shift is repeated from the beginning. Such a shmoo tool can display not only such shmoo data but also partially enlarge the shmoo data and store the shmoo data and each parameter value in a tester memory.
JP 2003-315418 A

  However, in the conventional shmoo tool, even if a plurality of DUTs are collectively tested using the multi-shmoo function described above, the display on the user interface of the shmoo tool is limited to one, and two or more In order to compare the shmoo data, each shmoo data must be displayed in the main area at a different timing, and the difference must be estimated based on the user's memory. In addition, when continuously checking the shmoo data of a plurality of DUTs, they can only be sequentially displayed in the main area, and the plurality of shmoo data cannot be viewed simultaneously.

  Also, if you want to perform a logical calculation between multiple shmoo data, change the mode on the shmoo tool, re-run the target DUT shmoo, and calculate the logical sum in units of partial data at the same time as the test. It needed to be processed. As described above, the conventional shmoo tool has a sufficient function for browsing the shmoo data of a single DUT, but lacks a function to obtain a correlation between a plurality of DUTs. Since the shmoo is executed, unnecessary analysis time such as 10 seconds to 1 hour is spent per shmoo. In recent years, DUTs targeted for device testers have also become denser and more complicated, and such a long analysis time by a shmoo tool has led to a reduction in time efficiency of device tests.

  Furthermore, the conventional shmoo tool only has a logical sum as a logical calculation, and a sufficient analysis cannot be performed.

  The present invention has been made in view of the above-mentioned problems of the conventional device tester, and an object of the present invention is to easily grasp the overall trend of shmoo data of a plurality of DUTs, and to provide a plurality of DUTs. Is to provide a new and improved device tester that can be calculated using various logical expressions without the need for a second shmoo acquisition.

  In order to solve the above problems, according to an aspect of the present invention, a device tester that performs an electrical test of a device under test, a shmoo acquisition unit that acquires shmoo data of a plurality of devices under test, and an acquisition One or two or more pieces of shmoo data from the plurality of shmoo data are transmitted to the user through a data storage unit for storing the plurality of shmoo data in the tester memory and a shmoo tool for selectively displaying the shmoo data on the display unit. There is provided a device tester, comprising: a data selection unit to be selected, and a preview function unit that displays one or more selected shmoo data juxtaposed on the display unit at a time.

  With the configuration of the preview function unit, a plurality of shmoo data can be viewed at the same time, so that it is easy to grasp the overall tendency of the shmoo data and the difference between the shmoo data. In addition, since a plurality of shmoo data is displayed in a list, specific shmoo data, for example, shmoo data different from other, shmoo data determined to fail, or specific partial data becomes a pass or fail. It is possible to specify the shmoo data and the like that is easy and in a short time.

  In order to solve the above problems, according to an aspect of the present invention, a device tester that performs an electrical test of a device under test, a shmoo acquisition unit that acquires shmoo data of a plurality of devices under test, and an acquisition One or two or more pieces of shmoo data from the plurality of shmoo data are transmitted to the user through a data storage unit for storing the plurality of shmoo data in the tester memory and a shmoo tool for selectively displaying the shmoo data on the display unit. A data selection unit to be selected, and a correlation display unit that logically calculates the selected one or two or more pieces of shmoo data in units of partial data and displays the calculated correlation shmoo data on the display unit. A device tester is provided.

  In the conventional device tester, the DUT to be subjected to the logic calculation is shuffled again. In the present invention, the correlation between a plurality of shmoo data can be calculated using various logical expressions using the already obtained shmoo data without performing re-acquisition of the shmoo data. Therefore, the analysis time of shmoo data can be shortened, and the overall test time can be improved.

  The logical calculation may be a calculation based on one or more logical operators selected from the group of OR, AND, NOR, NAND, XOR, and XNOR. For example, it is possible to derive the maximum frame of shmoo data by the OR operator, the common frame of pass or fail by the AND operator, and the difference between the two shmoo data by the XOR operator.

  The device number display unit further includes a device display unit that displays the device numbers of a plurality of shmoo data at the same time on the display unit, and the data selection unit can select the shmoo data by pointing the displayed device numbers.

  With this configuration, the user can make a new selection or selection while grasping which range of the shmoo data of all the shmoo data has been selected and how much of the shmoo data has been selected. Therefore, the shmoo data can be selected with an appropriate distribution and number. Further, the list of device numbers may be linked to the same DUT in the list of shmoo data. When one is selected, it is indicated that the other is also selected, and the correspondence relationship is visually checked. Can be easily grasped.

  It may further include a partial extractor that displays the device numbers of all the shmoo data in which the partial data in the same location as the specific partial data of any shmoo data is juxtaposed on the display at a time.

  With this configuration, it is possible to refer to all shmoo data in which specific partial data is passed or failed in a list format, and it is possible to easily grasp the tendency of the pass or fail related to the partial data. Further, since the extracted shmoo data can be further previewed, the shmoo data of interest can be compared with the shmoo data having the same tendency, and the efficiency of data analysis can be improved.

  It may further include a previous extraction unit that displays the device numbers of the devices under test that have passed or failed in the previous test in parallel with each other and displayed on the display unit.

  In general, the device test includes a series of partial test processes, and pass / fail is determined in each partial test process. The shmoo data of the present invention can be executed in the middle of the partial test process, and analyzes why a failure occurred in the partial test process immediately before. With the configuration of the present invention that displays a list of device numbers of devices under test that have passed or failed in the previous test, it is possible to identify the shmoo data to be analyzed in a short time, and to improve the efficiency of data analysis Can do.

  As described above, the device tester according to the present invention makes it easy to grasp the overall tendency of the shmoo data of a plurality of DUTs, and the correlation between the plurality of DUTs can be calculated with various logical expressions without acquiring the shmoo again. Can be used to calculate.

  Exemplary embodiments of the present invention will be described below in detail with reference to the accompanying drawings. In addition, in this specification and drawing, about the component which has the substantially same function structure, duplication description is abbreviate | omitted by attaching | subjecting the same code | symbol.

  After setting the DUT, the device tester according to the embodiment of the present invention applies a test signal to the DUT according to a pattern program in which the test order is written, and acquires a signal output from the DUT accordingly. In addition, the shmoo tool provided in the device tester derives the electrical characteristics of the DUT by changing correlated test parameters such as voltage and input / output timing set in the DUT. In order to facilitate understanding regarding such DUT testing, the overall structure of the device tester will be described first.

(First embodiment: device tester 100)
FIG. 1 is a block diagram illustrating a schematic configuration of a device tester 100 according to the first embodiment. The device tester 100 includes a main body 110 and a test head 120. A performance board 130 is placed on the test head 120, and a DUT 140 is placed on the performance board 130.

  The main body 110 is provided with a central control unit 114 that performs a preset test process via a user interface 112 including a display unit and a keyboard. The test head 120 is also referred to as a relay card (PE (Pin Electronics) card) including, for example, a test terminal connected to each device terminal of the DUT 140 and a pin module connected to the test terminal and performing a test function in units of 32. .) 122 is provided. The relay card 122 reflects a command related to the function test from the main body 110 on the test terminal.

  The performance board 130 can be fitted to the test head 120 and can be mounted with the DUT 140, and electrically connects a plurality of test terminals to the device terminals of the DUT 140.

  In the present embodiment, the central control unit 114 applies a test signal to the DUT 140 via the relay card 122 and captures a signal from the DUT 140. At this time, the device tester 100 determines whether or not the test target DUT 140 outputs a desired voltage at a desired timing (pass / fail).

  The allowable range for passing the DUT 140 must be a range in which it can be determined that the DUT 140 is operating normally. However, since various electrical elements in the DUT 140 affect the determination of the range in a complicated manner, it is difficult to uniquely determine the range by calculation. Therefore, using the shmoo tool according to the present embodiment, the electrical characteristics of the plurality of DUTs 140 are extracted to derive appropriate test parameters, and whether or not the determination based on such test parameters is appropriately performed. Check.

  In the device tester 100 of the present embodiment, in addition to a main window (FIG. 7) for performing a normal shmoo tool, a subwindow for performing a batch display of a plurality of shmoo data and a logical calculation is proposed. In addition, it is possible to quickly grasp the overall trend of a plurality of shmoo data and the correlation between each shmoo data. Hereinafter, hardware necessary for performing the shmoo tool will be described, and then detailed functions related to the sub-window will be described.

  FIG. 2 is a functional block diagram showing a hardware configuration when the device tester 100 performs a shmoo tool. The device tester 100 includes a central control unit 114, a tester memory 210, a display unit 212, and an operation unit 214.

  The central control unit 114 includes an integrated circuit such as a CPU, and manages and controls the entire device tester 100. Further, input / output of a test signal to the DUT 140 of the relay card 122 is controlled according to a test program for performing the test. Furthermore, it is possible to perform a shmoo that derives the electrical characteristics of the DUT 140 by changing correlated test parameters such as voltage and input / output timing set in the DUT 140.

The tester memory 210 is composed of ROM, RAM, E ² PROM, nonvolatile RAM, flash memory, HDD (Hard Disk Drive), etc., and programs and shmoo tools processed by the central control unit 114, as well as shmoo Stores the shmoo data acquired by execution.

  The display unit 212 includes a color or monochrome display, and can check the test result of the device test and the shmoo data graphically via the user interface of the shmoo tool.

  The operation unit 214 includes switches such as a mouse, a keyboard, a cross key, and a joystick, and accepts a user operation input. In particular, a pointing device such as a mouse can be used to designate a device number of a selection area described later.

  The hardware configuration for performing the shmoo tool in the device tester 100 has been described with reference to FIG. 2, and the functions and operations performed on such hardware will be described in detail below.

  FIG. 3 is a functional block diagram showing schematic functions in the performance of the shmoo tool of the device tester 100, and FIG. 4 is an external view showing a user interface of the shmoo tool, particularly a subwindow. The central control unit 114 of the device tester 100 uses the program in the tester memory 210 to correlate the shmoo acquisition unit 310, the data storage unit 312, the data selection unit 314, the device display unit 316, and the preview function unit 318. It functions as a display unit 320, a re-display unit 322, a partial extraction unit 324, and a previous extraction unit 326.

  The shmoo acquisition unit 310 acquires shmoo data of one or more DUTs 140 by executing shmoo. Shmoo is a program that examines how the pass / fail is affected by sequentially changing the determination range in order to determine the validity of the input / output of the DUT 140. Then, by plotting the derived shmoo data on the display unit 212 as a two-dimensional or higher graph, the overall characteristics can be provided to the user. Shmoo can be defined by either the input signal or the output signal of the DUT 140. The acquired shmoo data is used as reference data for determining an appropriate range under such plot observation and determining the test range during mass production.

  The data storage unit 312 stores the acquired plurality of shmoo data in the tester memory 210.

  The data selection unit 314 causes the user to select one or more shmoo data from a plurality of shmoo data stored in the device tester 100 through the shmoo tool.

  Referring to FIG. 4, the “select all DUTs” 422 in the selection block 420 of the shmoo tool sub-window 400 causes all DUTs 140 that can be tested to be selected to be selected. For example, when 512 DUTs 140 are connected, all 512 DUTs 140 are selected by pressing the “select all DUTs” 422. “Acquisition DUT selection” 424 causes all DUTs 140 for which shmoo data has been acquired to be selected. For example, when only 1 to 256 DUTs 140 are shmooked in the previous device test, all the acquired DUTs 140 are selected.

  “FAILDUT selection” 426 allows selection of only the DUT 140 that has failed in the immediately preceding test in a plurality of test steps. When the failure occurs continuously, the “FAILDUT selection” 426 is used to identify the DUT 140 in which the failure has occurred. “Deselect” 428 deselects all currently selected DUTs 140.

  The device display unit 316 displays a plurality of shmoo data device numbers in parallel in the selection area 480 of the display unit 212 at a time.

  The device tester 100 can test many DUTs 140 such as 512 at a time, and the number tends to increase in the future. Therefore, it is important how the desired shmoo data can be quickly identified from the many shmoo data corresponding to the DUT 140 on the shmoo tool. Therefore, the device display unit 316 displays a list of device numbers, and the data selection unit 314 can select shmoo data by pointing the displayed device numbers.

  With this configuration, the user can make a new selection or check while knowing which range of the shmoo data is selected among all the shmoo data, and how much of the shmoo data is selected. Since the selection can be canceled, the shmoo data can be selected with an appropriate distribution and number.

  Here, the user selects the pointer by overlapping the device number with the operation unit 214 such as a mouse or a touch pen, and the data selection unit 314 prepares the shmoo data for the designated device number. Such a selection can be made by left clicking or the like on a plurality of device numbers, and if the same processing is performed again, only the device numbers can be deselected. It is also possible to select a plurality of DUTs 140 at once by dragging or the like.

  The preview function unit 318 displays the selected one or more shmoo data juxtaposed in the main area 490 of the display unit 212 at a time. This preview function is performed by checking “Preview” 434 in the display block 430, and the shmoo data of the selected device number is displayed in the default display format. Such a display format can be changed by each item of the preview block 440. For example, the “size” 442 is formed by a list of “large”, “medium”, and “small”, and the size of the shmoo data displayed on the screen can be selected. In addition, the total number of the selected DUTs 140 is recorded in “total” 444, and referring to this, “digit” 446 and “row” 448 are adjusted to change the display format to a user-friendly layout desired by the user. Can do.

  After the preview function is performed, the main area 490 and the selection area 480 are linked, and the same DUT in both areas is linked with respect to the display format. For example, when one piece of shmoo data in the main area 490 is selected, the device number itself, the frame or the background color of the selection area 480 changes accordingly, and the newly selected shmoo data in the selection area 480 is the main data. When in the area 490, the frame color changes. In this way, it is possible to easily grasp the correspondence between the two areas visually. Such an interlocking function is effective in selecting a smaller number of device numbers while referring to the preview screen after selecting a plurality of device numbers.

  When the shmoo data displayed in the main area 490 is selected (double-clicked), the data selection unit 314 can display the selected shmoo data on the main window. When the same operation is performed again, the above processing displayed on the main window is canceled.

  With the configuration of the preview function unit 318, a plurality of shmoo data can be viewed at the same time, so that it becomes easy to grasp the overall tendency of the shmoo data and the differences between the shmoo data. In addition, since a plurality of shmoo data is displayed in a list, specific shmoo data, for example, shmoo data different from other, shmoo data determined to fail, or specific partial data becomes a pass or fail. It is possible to specify the shmoo data and the like that is easy and in a short time.

  The correlation display unit 320 logically calculates one or two or more shmoo data selected by the data selection unit 314 in units of partial data, and displays the calculated correlation shmoo data in the main area 490 of the display unit 212. To do. The logical calculation is formed by a list of OR, AND, XOR, NAND, NOR, and XNOR in the “operator” 452 of the superposition block 450, and the user selects one logical operator therefrom. For example, it is possible to derive the maximum frame of shmoo data by the OR operator, the common frame of pass or fail by the AND operator, and the difference between the two shmoo data by the XOR operator.

  Further, when the correlation shmoo data displayed in the main area 490 is selected (double-clicked), the correlation shmoo data can also be displayed in the main window. Further, by using the correlation display unit 320 and the preview function unit 318 in combination, for example, the preview function unit 318 narrows the shmoo data from five to two, and then the correlation display unit 320 uses the two correlations. Can be taken.

  The re-display unit 322 reflects the currently selected shmoo data by the user's “re-display” 460 operation. Therefore, the preview function unit 318 and the correlation display unit 320 are executed with the press of the “redisplay” 460 as a trigger. This is because the preview function and logical calculation take time, and the load increases if calculation processing is performed each time a device number is sequentially selected. Therefore, if calculation processing can be performed instantaneously, calculation processing is performed every time a device number is selected, and the preview function unit 318 and the correlation display unit 320 can be executed without pressing the “redisplay” 460. It becomes.

  In the conventional device tester, the DUT to be subjected to the logic calculation is shuffled again. In the present embodiment, the correlation between a plurality of shmoo data can be calculated using various logical expressions using the already obtained shmoo data without performing re-acquisition of the shmoo data. Therefore, the analysis time of shmoo data can be shortened, and the overall test time can be improved.

  The partial extraction unit 324 displays the device numbers of all the shmoo data having the same partial data as the specific partial data of any shmoo data in parallel in the main area 490 of the display unit 212 and displays them.

  FIG. 5 is an external view showing another example of the sub-window of the shmoo tool. The user selects specific partial data in a state where arbitrary shmoo data is displayed in the main area 490, and then presses the “selected plot P / F” 436 in the display block 430. As a result of this operation, the partial extraction unit 324 determines whether the specific partial data selected by the user is a pass or a fail, and for the partial data at the same location, the shmoo data and the pass / fail that were displayed first. Extract all shmoo data with equal. As shown in FIG. 5, a list of device numbers of the shmoo data extracted in this way is displayed in the main area 490 of the sub window 400.

  With this configuration, it is possible to refer to all shmoo data in which specific partial data is passed or failed in a list format, and it is possible to easily grasp the tendency of the pass or fail related to the partial data. In addition, since the extracted shmoo data can be selected and displayed by the preview function, the shmoo data of interest can be compared with the shmoo data having the same tendency, and the efficiency of data analysis can be improved.

  The immediately preceding extraction unit 326 displays the device numbers of devices under test that have passed or failed in the immediately preceding test in parallel in the main area 490 of the display unit 212 and displayed. The immediately preceding extraction unit 326 can be executed by pressing the “previous test P / F” 438 on the display block 430.

  In general, the device test includes a series of partial test processes, and pass / fail is determined in each partial test process. The shmoo data of this embodiment can be executed in the middle of the partial test process, and analyzes why a failure has occurred in the partial test process immediately before. With the configuration in which the device number of the device under test that has passed or failed in the previous test is displayed in a list by the previous extraction unit 326, the shmoo data to be analyzed can be specified in a short time, and the efficiency of the data analysis Can be achieved.

  The sub-window 400 described above is terminated when the user presses “Close” 470.

(Device test method)
Next, a device test method that enables various displays of shmoo data using the device tester 100 described above will be described.

  FIG. 6 is a flowchart showing the overall flow of the device test method. Referring to FIG. 6, in the device tester 100, first, test parameters are set using a shmoo tool (S600). Upon receiving a shmoo start signal from the user, the device tester 100 tests the plurality of DUTs 140 and acquires shmoo data (S602). The shmoo data acquired in this way is stored in the tester memory 210 (S604).

  Subsequently, the user opens the sub window 400 in addition to the main window by the shmoo tool (S606). Since the “preview” 434 of the display box 430 is selected as a default when the sub window 400 is started up, the shmoo data of the device number “1” is displayed in the main area 490 (S608).

  The device tester 100 selects all the device numbers that the user desires to display or perform logical calculation from the selection area 480 in which device numbers of a plurality of shmoo data are displayed in a list (S610). Then, it is determined whether the selection of the display block 430 when the “redisplay” 460 is pressed is “preview” 434 or “superimpose” 432 (S612).

  If “Preview” 434 is selected, the shmoo data of the device number selected by the user is displayed by the preview function (S614), and the device number selection (S610) is repeated. If “superimpose” 432 is selected, the partial data of the same location in the shmoo data is logically calculated between the shmoo data (S616), and the correlation shmoo data as the calculation result is displayed in the main area 490. (S618). The device number selection (S610) is repeated. At this time, the shmoo data that could not be displayed in the main area 490 is scroll-displayed through a scroll bar provided on the side of the main area 490.

  As described above, the device tester 100 according to the present embodiment makes it easy to grasp the overall tendency of the shmoo data of a plurality of DUTs, and the correlation between the plurality of DUTs can be obtained with various logics without acquiring the shmoo again. It is possible to calculate using the formula.

  As mentioned above, although preferred embodiment of this invention was described referring an accompanying drawing, it cannot be overemphasized that this invention is not limited to the example which concerns. It will be apparent to those skilled in the art that various changes and modifications can be made within the scope of the claims, and these are naturally within the technical scope of the present invention. Understood.

  Note that the steps in the device test method of the present specification do not necessarily have to be processed in time series in the order described in the flowchart, but are performed in parallel or individually (for example, parallel processing or object-based processing). Processing).

  INDUSTRIAL APPLICABILITY The present invention can be used for a device tester that can browse shmoo data using a shmoo tool.

It is a block diagram which shows the schematic structure of the device tester in 1st Embodiment. It is a functional block diagram showing a hardware configuration when performing a shmoo tool in the device tester in the same embodiment. It is the functional block diagram which showed the schematic function in performance of the shmoo tool of the device tester in the embodiment. It is the external view showing the user interface of the shmoo tool in the same embodiment, especially a subwindow. It is an external view showing the other example of the sub window of the shmoo tool in the same embodiment. It is the flowchart which showed the whole flow of the device test method in the embodiment. It is the external view which showed the user interface of the conventional shmoo tool.

Explanation of symbols

100 device tester 140 DUT
210 Tester Memory 212 Display Unit 310 Shmoo Acquisition Unit 312 Data Storage Unit 314 Data Selection Unit 316 Device Display Unit 318 Preview Function Unit 320 Correlation Display Unit 322 Redisplay Unit 324 Partial Extraction Unit 326 Immediate Extraction Unit

Claims (6)

A device tester for conducting an electrical test of a device under test,
A shmoo acquisition unit for acquiring shmoo data of a plurality of devices under test;
A data storage unit for storing the obtained plurality of shmoo data in a tester memory;
A data selection unit that allows the user to select one or more shmoo data from the plurality of shmoo data through a shmoo tool for selectively displaying the shmoo data on the display unit;
A preview function unit that displays the selected one or more shmoo data juxtaposed on the display unit at a time;
A device tester comprising: A device tester for conducting an electrical test of a device under test,
A shmoo acquisition unit for acquiring shmoo data of a plurality of devices under test;
A data storage unit for storing the obtained plurality of shmoo data in a tester memory;
A data selection unit that allows the user to select one or more shmoo data from the plurality of shmoo data through a shmoo tool for selectively displaying the shmoo data on the display unit;
A correlation display unit that logically calculates the selected one or two or more pieces of shmoo data in units of partial data and displays the calculated correlation shmoo data on a display unit;
A device tester comprising:   3. The device tester according to claim 2, wherein the logical calculation is a calculation based on one or more logical operators selected from the group of OR, AND, NOR, NAND, XOR, and XNOR. A device display unit further includes a device number of the plurality of shmoo data displayed in parallel on the display unit at a time,
The device tester according to claim 1, wherein the data selection unit causes shmoo data to be selected by pointing the displayed device number.   It further includes a partial extractor for displaying the device numbers of all the shmoo data having the same partial data as the specific partial data of any shmoo data in parallel on the display at a time. Item 5. A device tester according to Item 1-4.   The device tester according to claim 1, further comprising a previous extraction unit that displays device numbers of devices under test that have passed or failed in the previous test in parallel with each other and displayed on the display unit.

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