JP2013195168A - Resistivity measurement apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To precisely examine a change of a sample due to aging with simple operation.SOLUTION: A resistivity measurement apparatus includes a 4-probe resistivity measurement device 100 which measures a resistivity of a sample, and a personal computer 1. The personal computer 1 stores setting information for measuring the sample in a memory table 91, and stores a measurement schedule including a measurement period and a measurement interval in a measurement schedule management table 92. The personal computer 1 causes the 4-probe resistivity measurement device 100 to measure the resistivity of the sample on the basis of the measurement schedule and the setting information, and associates the obtained measurement data with a measurement time in each measurement and stores the measurement data in the memory table 91.

Description

  The present invention relates to a resistivity measuring apparatus that measures the resistivity of a sample such as a semiconductor wafer.

  Conventionally, when measuring the resistivity of a sample such as a semiconductor wafer with a four-probe resistivity meter, an ordinary measurement method is used, and the measurement period and measurement interval are arbitrarily set by an operator. The normal measurement method is a method in which measurement is performed only once, or measurement is performed continuously at an arbitrary designated number of times without a measurement interval.

  However, when the measurement result is different from the expected value during the normal measurement operation, it is necessary to determine whether the cause is due to the aging of the wafer or the failure of the measuring instrument. For this reason, it is necessary to investigate the change with time of the wafer separately from each measurement. The change with time of the wafer varies depending on the material used, and observation over a long period of one month or more is required. In the case of some ion-implanted layer wafers, it is known that the resistivity changes with time due to factors other than natural oxidation of the layer surface. In addition, the change in the resistivity of the wafer is influenced not only by time but also by changes in temperature and humidity during measurement.

  Therefore, as a conventional technique, a technique for preventing a decrease in measurement accuracy due to a difference in temperature during resistivity measurement has been proposed (see, for example, Patent Document 1).

JP 2000-275286 A

  As described above, the conventional resistivity measuring apparatus does not have a measurement function for measuring the change of the wafer over time, and uses a conventional normal measurement function and an inspection function at the time of shipment. Measurement work has been done. For this reason, it is necessary for the operator to manually set the measurement parameters used for measurement and start the measurement, and the operator has manually performed the measurement work for the temporal change investigation every time. For this reason, when performing measurements at intervals within a certain period, it is necessary for the operator to perform an operation according to the measurement procedure for each measurement, and therefore there is no measurement parameter selection error or measurement interval deviation. Could have occurred. In addition, the measurement time is limited to the worker's working hours, and when the person is absent, a third party regularly performs or there is no measurement, and periodic measurement may not be possible. .

  Moreover, in order to obtain a measurement result, it is necessary for an operator to process data obtained individually for each measurement. If the amount of data is large, the work time for data processing becomes long. When measuring the time-dependent change of a wafer in response to a survey request from a customer, the operator must continue the manual measurement periodically until the wafer is returned to the customer.

  The present invention has been made paying attention to the above circumstances, and an object of the present invention is to provide a resistivity measuring apparatus capable of accurately investigating a temporal change of a sample by a simple operation.

  In order to achieve the above object, a first aspect of the present invention includes a measurement means for measuring a resistivity of a sample, a means for storing measurement conditions for measuring the sample, a measurement period, and a measurement interval. Means for storing a measurement schedule; means for causing the measurement means to measure the resistivity of the sample based on the setting information according to the measurement schedule; and storing measurement data obtained for each measurement in association with a measurement time And a resistivity measuring device.

  According to the first aspect, it is possible to automatically perform continuous measurement on the same wafer under the same conditions by setting a measurement period and a measurement interval, for example, when investigating changes with time of the wafer. . Such a configuration eliminates the need for the operator to perform an operation according to the measurement procedure for each measurement, thereby avoiding measurement condition selection errors and measurement interval deviations.

According to a second aspect of the present invention, in the first aspect, means for generating a two-dimensional image or a three-dimensional image representing a change with time of the resistivity of the sample based on the measurement data obtained within a predetermined period. Furthermore, it is equipped.
According to the second aspect, for example, measurement data acquired during the measurement period can be read in a lump, so that graphs such as “deviation”, “contour lines”, “3D”, etc. can be automatically generated. Become.

According to a third aspect of the present invention, in the first aspect, the apparatus further includes means for receiving other setting information within the measurement period of the measurement schedule and causing the measurement means to measure.
According to the 3rd aspect, since a single measurement and another continuous measurement can be performed also during the continuous measurement by a measurement schedule, it becomes possible to implement a resistivity measurement more efficiently.

  That is, according to the present invention, it is possible to provide a resistivity measuring apparatus capable of accurately investigating a change with time of a sample with a simple operation.

The block diagram which shows the structure of the resistivity measuring system which concerns on this invention. The flowchart which shows operation | movement of a resistivity measurement system. The figure which shows a measurement main screen (in normal mode). The figure which shows a measurement main screen (in continuous measurement mode). The figure which shows a recipe registration screen. The figure which shows a measurement pattern registration screen. The figure which shows a measurement mode registration screen (at the time of normal mode setting). The figure which shows a measurement mode registration screen (at the time of continuous measurement mode setting). The figure which shows the display screen at the time of an error. The figure which shows the notification screen before a measurement. The figure which shows the outline | summary of the memory table of a measurement parameter and a measurement result. The figure which shows an example of the registration content of a measurement parameter (recipe) area. The figure which shows an example of the registration content of a measurement data area. The figure which shows an example of the registration content of a measurement schedule management table. The figure which shows a measurement schedule screen (no error). The figure which shows a measurement schedule screen (with an error). The figure which shows a measurement result display screen. The figure which shows a measurement result display screen (line graph at the time of normal mode). The figure which shows a measurement result display screen (line graph at the time of continuous measurement mode). The figure which shows a measurement result display screen (contour map at the time of continuous measurement mode). The figure which shows a measurement result display screen (3D figure at the time of continuous measurement mode).

Embodiments according to the present invention will be described below with reference to the drawings.
FIG. 1 is a block diagram showing a configuration of a resistivity measurement system according to the present invention. As shown in FIG. 1, this resistivity measurement system includes, for example, a four-probe resistivity measuring instrument 100 that measures the resistivity of a semiconductor wafer or the like, and a personal computer (PC) that controls the four-probe resistivity measuring instrument 100. ) 1, a main power supply 2, an uninterruptible power-supply system (UPS) 8, and a storage device 9. The 4-probe resistivity measuring instrument 100 is a control unit 3 that controls communication with the PC 1 and controls other units, a power supply unit 4, and a signal distribution unit that distributes control signals transmitted from the control unit 3 to each unit. 5. A probe 6 for measuring a measurement value and a measurement unit 7 are provided.

  The PC 1 performs system control and control of the 4-probe resistivity measuring instrument 100. A storage device 9 is connected to the PC 1 to manage a memory table 91 and a measurement schedule management table 92 which will be described later. The control of the 4-probe resistivity measuring instrument 100 is performed according to the setting contents of the measurement parameters stored in the memory table 91 and the measurement schedule management table 92.

The main power supply 2 supplies power to the UPS 8 and the 4-probe resistivity measuring instrument 100. The power of the PC 1 is supplied via the UPS 8.
The control unit 3 transmits a control signal for controlling each unit according to the control based on the setting contents of the measurement parameter from the PC 1. Further, the measurement result from the measurement unit 7 is notified to the PC 1. The PC 1 is also notified of the operation status of each unit.

The power supply unit 4 creates an operating voltage used in the measurement unit 7.
The signal distribution unit 5 distributes the control signal from the control unit 3 to each unit.
The probe 6 is composed of, for example, a four-probe probe. Since there is a limit on the number of uses, it is necessary to know the number of uses during operation. The probe operation is controlled by a control signal from the control unit 3.

  The measurement unit 7 is connected to a main power supply 2, a measurement unit power supply unit 4, a signal distribution unit 5 that distributes a signal from the control unit 3, and a probe 6 that measures a measurement value. The measurement unit 7 converts the measurement value from the probe 6 into a digital value in accordance with the control signal sent from the control unit 3 via the signal distribution unit 5, and passes the signal distribution unit 5 to the control unit 3. To notify.

The UPS 8 supplies power supplied from the main power supply 2 to the PC 1. When the power supply is cut off due to a power failure or the like, the power is supplied for a certain period of time. The PC 1 terminates the system within a certain time after the power is turned off.
FIG. 2 is a flowchart showing the operation of this resistivity measurement system. FIG. 3 shows a measurement main screen (in normal mode), and FIG. 4 shows a measurement main screen (in continuous measurement mode). From the screen of FIG. 4, the continuous measurement mode can be stopped and the measurement schedule can be referred to. In the present embodiment, the normal mode is a method of performing measurement only once, and the continuous measurement mode is a method of performing measurement at an arbitrary measurement interval during a set measurement period. By providing the continuous measurement mode and the normal mode and making the discrimination possible by the PC 1, the measurement completion can be automatically determined.

  In step S1 of FIG. 2, first, since measurement parameters need to be set before measurement, new measurement parameters are created or read. Select a measurement parameter that has already been registered from the measurement parameter list on the measurement main screen in the normal mode in FIG. 3 or the measurement main screen in the continuous measurement mode in FIG. 4 or click the “New” button to create a new measurement parameter. Create The measurement parameter is setting information about the measurement content of the measurement target wafer, and includes a recipe, a measurement pattern, and a measurement mode. Since the measurement parameter has many items, the screen is divided as shown in FIGS.

FIG. 5 shows a recipe registration screen. From this screen, the file name, lot ID, etc., the measurement result calculation formula, recipe, and measurement conditions are set. The recipe includes the type and size of the wafer. Measurement conditions include measurement type, range, measurement method, and measurement range.
FIG. 6 shows a measurement pattern registration screen. Set the measurement position, number of points, edge mask, etc. from this screen. As the measurement position or the like, a pattern commonly used in the four-probe measurement can be used, or an arbitrary position can be designated.

FIG. 7 shows a measurement mode registration screen (when the normal mode is set). As shown in FIG. 7, in the normal mode, since other setting items on the screen are not used, they cannot be set.
FIG. 8 shows a measurement mode registration screen (when continuous measurement mode is set). The measurement schedule in the continuous measurement mode can specify a measurement period and a measurement interval therebetween. As the measurement interval, a fixed interval or a measurement interval for each time can be arbitrarily designated. Furthermore, it is possible to set the processing when an error occurs during measurement and the time for notification on the screen before measurement.

  The item “at the time of measurement error” in FIG. 8 sets processing such as skipping measurement when an error occurs in order to cope with a situation where a wafer is not prepared during the continuous measurement mode. FIG. 9 shows an example of a display screen at the time of error. In the continuous measurement mode or the normal mode, if an error occurs before measurement and the error content is not resolved even after waiting for a certain time, the operator is notified with a screen display as shown in FIG. Since the measurement work cannot be performed when an error occurs, the measurement is not performed in the continuous measurement mode, and the measurement work is terminated. This screen is automatically closed in accordance with the operator's operation of the “Close” button or after a predetermined time has elapsed.

  The item “notification time before measurement start” in FIG. 8 is used to set a time for notification to the operator on the screen display when the measurement start time is near in the continuous measurement mode. This notification is performed on, for example, a pre-measurement notification screen as shown in FIG. 10, and this screen is automatically closed in accordance with the operator's “close” button operation or at the start of measurement.

  For example, as shown in FIG. 11, the measurement parameters and the measurement results are stored in the memory table 91 separately in a measurement parameter (recipe) area and a measurement data area. The measurement result is referred to using “measurement parameter” as a key. Details of the measurement parameter and measurement result storage area are shown in FIGS.

  In the measurement parameter (recipe) area, for example, as shown in FIG. 12, registered contents for each set of measurement parameters (recipe) are stored. Since the number of measurement points in the measurement parameter is variable data, “end of measurement parameter (recipe)” is registered as an end flag for one set. When this flag is read out, it is determined that the last registered data for one set of measurement parameters.

  In the measurement data area, for example, as shown in FIG. 13, the measurement data for each measurement result is registered in the order of measurement. Since the number of measurement points in the measurement result is variable data, “end of one measurement value data” is registered as an end flag for one time. When this flag is read, it is determined that the last registered data for one measurement value data. Data reading in the continuous measurement mode is performed in accordance with the “measurement mode” and “number of measurements” in the measurement result registration contents (in the continuous measurement mode, the “measurement number” in FIG. Is registered). “Continuous measurement No.” is a combination of the number to be incremented every time the continuous measurement mode is set and the number of measurements. For example, when the continuous measurement mode setting is “fourth” and the number of continuous measurements is the third measurement, “continuous measurement No.” = “0403” is registered in the “measurement number” in the measurement result.

  When the continuous measurement is completed, the “measurement count” is registered as the incrementing number + “0”, and is recognized as the final measurement count data of the continuous measurement. When measurement stop is set during the continuous measurement mode, reading is performed from the last registered measurement result toward the beginning of the measurement result. Since the content of the “measurement count” in the continuous measurement mode registered later is the last result of the corresponding continuous measurement mode, the “measurement count” is changed to an incrementing number + “0”. With this procedure, the measurement result can be read correctly even if the measurement is interrupted. In the case of the normal mode, the contents of “continuous measurement No.” in FIG. 14 are registered as “measurement count” in FIG. 13, so “measurement count” = “0000” is registered.

  Management of the measurement schedule is managed by a measurement schedule management table 92 provided in a memory area different from the memory table 91 in which measurement parameters and measurement results are stored. FIG. 14 shows an example of registered contents of the measurement schedule management table 92. The measurement schedule management table 92 includes items such as “number”, “continuous measurement NO.”, “Number of times of measurement execution”, “notification time”, “measurement date and time”, and “recipe file name” before the start of measurement. . The “number” is assigned the order in which the order of measurement is registered and the reserved date and time are closest.

  The measurement schedule can be confirmed by displaying the measurement schedule screen shown in FIG. 15 by the “measurement schedule” button on the measurement main screen in the continuous measurement mode of FIG. FIG. 15 is an example of a display screen of the contents managed by the measurement schedule management table 92, and is a screen displayed when no measurement error has occurred. When a measurement error occurs, it is displayed as shown in FIG. The schedule can be changed (only deleted) from the measurement schedule screen. When the “update” button is pressed after changing the schedule, the PC 1 updates the registered content of the measurement schedule management table 92. Also, the schedule and registered contents are updated when measurement is started or completed in the continuous measurement mode, or when the continuous measurement mode is stopped.

  After the measurement parameter setting in step S1 is completed, in step S2, when the operator selects the “measurement start” button on the measurement main screen in FIG. 3 or FIG. 4, the PC 1 is used for measurement. The measurement parameters are read from the measurement parameter (recipe) area shown in FIG. 12, and resistivity measurement is started (step S3). In step S4, in the continuous measurement mode, the PC 1 checks whether the measurement interval during measurement parameter setting and the currently registered measurement schedule do not overlap. When there is no duplication of measurement schedule and the measurement in the continuous measurement mode is started, the PC 1 updates the registered content of the measurement schedule management table 92.

  If measurement schedule duplication has occurred as a result of the schedule confirmation in step S4 (step S5: with schedule error), the PC 1 displays the measurement schedule screen (with error) in FIG. 16 and notifies the operator of the error. . From the screen of FIG. 16, the operator can delete the schedule in error. When the “update” button is pressed after changing the schedule, the PC 1 updates the registered contents of the measurement schedule management table 92.

  If it is determined in step S5 that there is no error (step S5: NO) and the measurement operation is started without any problem, the PC 1 displays the measurement result display screen of FIG. 17 (step S6). During the measurement, the measured values that have been measured on this screen are updated in real time. In the continuous measurement mode, as shown in FIG. 4, “in continuous measurement mode” is displayed on the measurement main screen, and the next measurement scheduled time and the like are notified.

  When the next slot is measured (step S7: YES), the process proceeds to step S3. If there is no measurement in the next slot (step S7: NO), after one measurement is completed (step S8), the recipe and the measured value are stored (step S9). The PC 1 stores the recipe and measurement values in the measurement data area shown in FIG. 13 for each measurement result. Also, the PC 1 updates the registered contents of the measurement schedule management table 92. The PC 1 calculates values such as “maximum value”, “minimum value”, “intermediate value”, and “average value” from the measurement value obtained in step S9, and displays it on the measurement result display screen of FIG. To do. When referring to the measurement results, select the corresponding file name from the measurement main screen in the normal mode in FIG. 3 or the measurement main screen in the continuous measurement mode in FIG. 4 and press the “Details” button, as shown in FIG. A measurement result display screen opens, and the measurement result can be referred to.

In the measurement result display screen, in the case of the continuous measurement mode, “deviation”, “contour line”, and “3D” graph display can be performed using measurement value data obtained within a certain period.
The measurement result display screen (line graph in the normal mode) shown in FIG. 18 is a screen display example when measurement in the normal mode is completed and “deviation” is selected on the measurement result display screen in FIG.

  The measurement result display screen (a line graph in the continuous measurement mode) shown in FIG. 19 is a screen display example when measurement in the continuous measurement mode is completed and “deviation” is selected on the measurement result display screen in FIG. . The results for the number of measurements completed from the start of continuous measurement are displayed on the line graph screen.

  The measurement result display screen (contour map in the continuous measurement mode) shown in FIG. 20 is a screen display example when the measurement in the continuous mode is completed and “contour lines” is selected on the measurement result display screen in FIG. A graph of the measurement results for one time is displayed, and in the case of continuous measurement mode, the results for the acquired number of times are sequentially displayed in such a manner that frames are displayed. The display screen can be operated by halfway, back and forth, pause, and stop.

  The measurement result display screen (3D diagram in the continuous measurement mode) shown in FIG. 21 is a screen display example when the measurement in the continuous mode is completed and “3D” is selected on the measurement result display screen in FIG. The measurement result for one time is displayed on a graph, and in the case of continuous measurement mode, the result for the acquired number of times is displayed with a frame-by-frame display. The display screen can be operated by halfway, back and forth, pause, and stop.

  The graph type is the same regardless of the mode type, but in the continuous measurement mode, the table for each measurement is displayed frame by frame, or the results for the number of times the measurement is completed are displayed in a batch graph. To do. As described above, the measurement result acquired in the continuous measurement mode can automatically create a graph summarizing the result so that the change with time can be easily understood.

  On the other hand, when the measurement is started in step S3 of FIG. 2, regardless of the measurement mode, if there is an error before measurement such as forgetting the placement of the wafer in step S5, the error is recovered within a certain time (step S14). : NO) proceeds to step S3. On the other hand, if an error continues to occur after a certain time has elapsed (step S14: YES), the PC 1 notifies the operator of an error before measurement on the error display screen as shown in FIG. 9 (step S15). ). Then, error processing is performed according to the processing setting contents at the time of measurement error set on the measurement mode registration screen (when the continuous measurement mode is set) in FIG. 8 (step S15).

  Also, before the measurement period elapses (step S10: NO) and before the measurement interval elapses (step S11: NO), when another measurement schedule or normal mode measurement is accepted, step S10 is performed. (Step S12: YES), if not (Step S12: NO), the measurement start is accepted (Step S13). Before the next measurement starts in the continuous measurement mode, the PC 1 displays the pre-measurement notification screen in FIG. 10 and notifies the operator to prepare the measurement start time and the wafer to be measured. The notification time is the contents registered as “pre-measurement notification time” in the measurement parameter. “Notification time before measurement” is set on the measurement mode registration screen (in continuous measurement mode) in FIG. As shown in the pre-measurement notification screen of FIG. 10, by notifying the worker near the measurement time, it becomes possible to perform another measurement work during the measurable period.

  If continuous measurement is in progress, the fact that the continuous measurement mode is in effect is displayed on the screen as in the measurement main screen in the continuous measurement mode in FIG. A plurality of continuous measurement modes can be registered, but can be canceled in the middle. To cancel, select a file name from the list of measurement parameters in the main measurement screen in the continuous measurement mode shown in FIG. When the “continuous measurement mode stop” button is pressed, the PC 1 updates the registered content of the measurement schedule management table 92.

  In FIG. 2, when the measurement period elapses or the continuous measurement mode is stopped and the continuous measurement mode ends (step S10: YES), and another continuous measurement mode is registered (step S16: YES). The process proceeds to step S10. On the other hand, if no other continuous measurement mode is registered (step S16: NO), the display of “in continuous measurement mode” is deleted as in the measurement main screen in the normal mode in FIG. Transition from the measurement mode to the normal mode (step S18).

  As described above, in the above-described embodiment, the measurement period and the measurement interval are set, and a continuous measurement mode capable of performing continuous resistivity measurement on the same wafer is newly provided. It becomes possible to provide the customer with a method in which the state of change in resistivity over time can be easily understood.

  Therefore, according to the above-described embodiment, it is possible to automatically perform wafer measurement using the same measurement parameter during a certain period without investigating the operator's operation during a certain period, such as when investigating a change with time. become. The measurement time can be assigned to a time when there is no operator, and the measurement work can be performed by preparing the wafer to be measured on the stage or placing it in an arbitrary slot in the wafer carrier of the transfer machine. Can be done.

  In addition, according to the above-described embodiment, since the operation becomes easy, it becomes easy to perform the measurement when the customer himself / herself conducts the time-dependent survey of the wafer. Since the measurement work can be automatically performed even when the worker is not working, the measurement work can be performed efficiently. Since the measurement data acquired during a certain period can be read at once, calculation of the change rate, deviation rate, and graphing can be automatically generated. The result obtained by the measurement is one of the determination conditions for determining whether the measurement result obtained by the normal measurement operation is different from the expected value or whether it is due to the aging of the wafer or the failure of the measuring instrument. Can be used as one.

  Note that the present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage. Further, various inventions can be formed by appropriately combining a plurality of constituent elements disclosed in the embodiment. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, you may combine suitably the component covering different embodiment.

  DESCRIPTION OF SYMBOLS 100 ... 4 probe resistivity measuring device, 1 ... Personal computer (PC), 2 ... Main power supply, 3 ... Control unit, 4 ... Power supply unit, 5 ... Signal distribution unit, 6 ... Probe, 7 ... Measurement unit, 8 ... Uninterruptible power supply (UPS), 9 ... storage device, 91 ... memory table, 92 ... measurement schedule management table.

Claims (3)

A measuring means for measuring the resistivity of the sample;
Means for storing setting information for measuring the sample;
Means for storing a measurement schedule including a measurement period and a measurement interval;
Means for causing the measurement means to measure the resistivity of the sample based on the setting information according to the measurement schedule;
And means for storing measurement data obtained for each measurement in association with the measurement time.   2. The resistivity according to claim 1, further comprising means for generating a two-dimensional image or a three-dimensional image representing a temporal change in the resistivity of the sample based on the measurement data obtained within a predetermined period. measuring device.   The resistivity measurement apparatus according to claim 1, further comprising means for receiving other setting information within a measurement period of the measurement schedule and causing the measurement means to measure.

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