JPH09245714A - Control method and focused ion beam device used therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To automatically correct distortion of a processor and perform focused ion beam processing with high precision by shifting focused ion beams being radiated based on a calculated distortion quantity and correcting the processor. SOLUTION: Specimens to be processed is marked by means of an FIB device, and the user inputs the interval time and mark scan count of a mark scan by means of an input device 12a. When processing is started, a data comparing part 12I judges whether or not mark scan count is above the maximum value, if it judges that the mark scan count is below the maximum value a central processing unit starts mark scanning, the center coordinate is detected, and data is stored in a storage portion 12g. When it judges that the mark scan count is above the maximum value, the mark scan position is shifted to a specified position. If the specimen is moving, the central processing unit 12k calculates the distortion quantity, outputs the calculation results to a scan controller 12d, and performs correction of the processor.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control method and a focused ion beam apparatus used for the control method, and more particularly to a technique effectively applied to automatic correction of a processing position deviation due to a focused ion beam.

[0002]

2. Description of the Related Art According to a study made by the present inventor, a focused ion beam, that is, an F beam is used when processing, analyzing, or observing the surface of a semiconductor wafer or a thin film.
Focused ion beam devices using the IB (Focused Ion Beam) technology are widely used.

When a semiconductor wafer is processed by this focused ion beam apparatus, the method of fixing a sample such as a semiconductor wafer or a semiconductor chip is to attach the sample placed on a stage with a carbon tape or the like. Has been done.

As an example in which the focused ion beam device is described in detail, published by Kogyo Kogyokai Co., Ltd., April 10, 1992, Takashi Hirao et al., "Basics and Applications of Ion Engineering Technology" P227-P234 This document describes the configuration and application technology of the focused ion beam device.

[0005]

However, in the method of fixing the sample in the focused ion beam apparatus as described above,
The inventors have found the following problems.

That is, since the sample is fixed only by the carbon tape, the sample itself may drift during the irradiation of the ion beam by the focused ion beam apparatus, and it is particularly reliable for a small sample such as a semiconductor chip. It tends to be difficult to fix.

Further, mechanical drift may occur from a stage moving gear or the like provided on the stage on which the sample is placed.

As a result, there is a problem in that the machining position is displaced, resulting in machining defects due to insufficient machining depth and disappearance of the observation position.

An object of the present invention is to provide a control method capable of automatically correcting a deviation of a processing position during irradiation of a focused ion beam and performing FIB processing with high accuracy, and a focused ion beam apparatus used for the control method. is there.

The above and other objects and novel features of the present invention will be apparent from the description of this specification and the accompanying drawings.

[0011]

SUMMARY OF THE INVENTION Among the inventions disclosed in the present application, the outline of a representative one will be briefly described.
It is as follows.

That is, the control method of the present invention detects the position of a predetermined mark by a line scan of a focused ion beam at every predetermined interval time, and the position of the mark detected first and the latest detected position. A step of comparing the position of the mark and calculating the amount of deviation between the position of the first detected mark and the latest detected mark, and shifting the focused ion beam during irradiation based on the calculated amount of deviation , And a step of correcting the processing position.

Accordingly, even if the processing position is deviated during the processing of the focused ion beam, the processing position can be automatically corrected, so that highly accurate processing can be performed.

Further, in the control method of the present invention, the mark is formed by irradiating a sample to be processed with a focused ion beam.

Thereby, the mark for recognizing the processing position can be easily formed.

Further, in the control method of the present invention, the step of comparing the deviation amount obtained in the step of calculating the deviation amount with a preset deviation amount, and the deviation amount in which the calculated deviation amount is set. If it is larger than the above, the correction time of a predetermined time is subtracted from the line scan interval time to shorten the interval time, and if there is no difference between the calculated deviation amount and the set deviation amount, the correction time is added to the interval time. And a step of extending the interval time.

As a result, when there is no deviation in the machining position, the line scan interval time is lengthened, and when the machining position is greatly misaligned, the line scan interval time is shortened. The sample can be processed with high accuracy while reducing the damage applied.

Further, the control method of the present invention compares the number of line scans in the step of detecting the position of a predetermined mark with a preset number of times, and when the number of line scans is equal to or greater than the preset number, focused ions are obtained. It has a step of shifting the line scan position by the beam.

Also by this, since the line scan position on the sample is periodically changed, the sample can be processed with high accuracy while reducing the damage to the sample.

Further, the focused ion beam apparatus according to the present invention has an input means for inputting an interval time for detecting the position of a predetermined mark on the sample, and a focused ion beam for each predetermined interval time input by the input means. Mark detection means for detecting by line scan, and position correction for correcting the machining position by shifting the focused ion beam during irradiation based on the amount of deviation between the position of the first detected mark and the position of the latest detected mark And means are provided.

Accordingly, even if the processing position is deviated during the processing of the focused ion beam, the mark detecting means can detect the deviation of the processing position and the position correcting means can automatically correct the processing position. Precision processing can be performed.

Further, the focused ion beam device of the present invention is
The mark detection means is controlled by the ion beam control means for generating an ion beam for irradiating the mark on the sample surface from the ion beam source at every predetermined interval time input by the input means, and the ion beam control means. Luminance modulation means for detecting secondary electrons or secondary ions emitted by irradiation with an ion beam and converting them into a brightness modulation signal, and waveform processing for converting the brightness modulation signal converted by the brightness modulation means into a waveform signal. Means, first control means for detecting the position data of the mark converted by the waveform processing means, and storage means for storing the position data first detected by the first control means. The position correction means compares the position data stored in the storage means with the position data of the mark most recently detected by the mark detection means, Calculating means for calculating a shift amount of the mark which is detected in the position and the latest mark was detected first,
The second control means is configured to shift the focused ion beam during irradiation based on the shift amount calculated by the calculation means and correct the processing position.

This makes it possible to accurately control the amount of positional deviation during processing, the length of the line scan interval time, and the like, and it is possible to process the sample with higher accuracy while reducing damage to the sample. it can.

As described above, it is possible to eliminate processing defects such as disappearance of the observation portion and insufficient processing in the cross-section processing of the sample, and it is possible to improve the processing yield in the focused ion beam apparatus.

[0025]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a structural explanatory view of a focused ion beam apparatus according to one embodiment of the present invention, FIG. 2 is a control circuit block diagram of the focused ion beam apparatus according to one embodiment of the present invention, and FIG. FIG. 4A is a control flowchart of the focused ion beam device according to the embodiment of the present invention.
FIG. 6B is an explanatory diagram of a method for detecting the positional deviation of the center coordinates of the mark formed on the sample according to the embodiment of the present invention.

In the present embodiment, a focused ion beam apparatus (hereinafter referred to as FIB apparatus) 1 for processing, observing, and analyzing and evaluating the surface of a sample such as a semiconductor wafer or a thin film surface has a chamber 2 which is a processing chamber. It is provided.

Further, in the FIB apparatus 1, a liquid metal ion source (L) for obtaining an ion beam by heating and melting a substance to be ionized in a vacuum at the top of the chamber 2 and applying a high electric field thereto.
MIS: Liquid Metal Ion Source
ce) gallium metal ion source (ion beam source)
3 are provided.

Further, the FIB apparatus 1 is provided with a first electrostatic lens 4 for focusing the ion beam obtained by the gallium metal ion source 3 below the gallium metal ion source 2, and the first electrostatic lens 4 is provided. An aperture 5 serving as a diaphragm of the lens is provided below the.

Further, in the FIB device 1, a second electrostatic lens 6 for focusing the ion beam is provided below the aperture 5 similarly to the first electrostatic lens 4, and the second electrostatic lens 6 is provided. A scanning coil 7 that scans an ion beam within a predetermined range is provided below.

In the FIB device 1, below the scanning coil 7, a detector (secondary electron or secondary ion emitted from the sample surface due to ion irradiation is detected, converted into a brightness modulation signal and imaged). A brightness modulating means) 8 is provided, and a stage 9 for mounting a sample is provided below the detector 8.

A stage drive unit is provided on the stage 9 so that the stage 9 can move based on a predetermined signal.

Further, the FIB device 1 is provided with a turbo pump 10 and a rotary pump 11 for evacuating the chamber 2 described above.

The gallium metal ion source 3,
The first electrostatic lens 4, the second electrostatic lens 6, the scanning coil 7,
The detector 8, the stage 9, the turbo pump 10, and the rotary pump 11 are controlled by the FIB controller 12 that controls the FIB device 1.

Further, the FIB device 1 is provided with a machining position,
A display unit 13 such as a monitor of the processing status and a monitor used for observing a cross section is provided.

Next, the configuration of the FIB controller 12 in the FIB device 1 will be described with reference to FIG.

First, the FIB controller 12 is provided with an input device (input means) 12a for inputting predetermined data and the like.

Further, the FIB controller 12 controls the ion source controller 12b for controlling the above-mentioned gallium metal ion source 3 (FIG. 1), the first electrostatic lens 4 and the second electrostatic lens 6 (FIG. 1). A lens controller 12c for performing the above is provided.

Further, the FIB controller 12 includes a scan controller (ion beam control means) 12d for controlling the scan coil 7 (FIG. 1), a stage controller 12e for controlling drive of the stage 9, a turbo pump 10, and a rotary pump 11. An exhaust system controller 12f that controls the exhaust system is provided.

Further, the FIB controller 12 has a storage section (storage means) 12g for storing predetermined data, and a waveform processing section (waveform processing for converting the luminance modulation signal detected by the detector 8 (FIG. 1) into a waveform. Means) 12h.

The FIB controller 12 also includes a data comparison section (data comparison means) 12 for comparing predetermined data.
An arithmetic unit (arithmetic means) 12j for arithmetically operating i and predetermined data is provided.

Then, the FIB controller 12
A central processing unit (first and second control means) 12k that controls all the controls in the IB device 1 is provided, and these input device 12a, ion source controller 12b, lens controller 12c, and scan controller 12 are provided.
d, stage controller 12e, exhaust system controller 12f, storage unit 12g, waveform processing unit 12h, data comparison unit 12i, calculation unit 12j, and display unit 13 (FIG. 1).
Is connected to the central processing unit 12k.

Then, the detector 8 (FIG. 1), the scan controller 12d, the storage section 12g, the waveform processing section (waveform processing means) 12h, the storage section 12g and the central processing section 1 are provided.
The mark detecting means is composed of 2k.

Further, the data comparison section 12i and the calculation section 12j.
In addition, the central processing unit 12k also constitutes a position correction means.

Next, the operation of the FIB controller 12 in this embodiment will be described with reference to the flowchart of FIG.

First, the sample to be processed is placed on the stage 9, and, for example, a cross-shaped mark is formed at a predetermined portion of the sample by the FIB device 1 and marking is performed (step S101).

Further, as the marking, a pattern having sharp edges formed on the semiconductor chip may be set as the mark without the FIB processing.

Then, the user uses the input device 12a to
The mark scan interval time and the number of mark scans are input (step S102). Here, the mark scan interval time is determined by the user, for example, based on the processing time of the sample, and the maximum value of the number of mark scans is set by the user in advance according to the material of the sample to be processed.

Next, the user inputs the processing start data with the input device 12a, and the processing is started (step S103). When the processing is started, the data comparison unit 12i
However, the number of mark scans by the FIB is determined in step S10.
It is determined whether or not it is equal to or larger than the mark scan maximum value input in 2 (step S104).

When the data comparison unit 12i determines that the number of mark scans is less than or equal to the maximum mark scan value, the central processing unit 12k starts the mark scan, and the intersection of the above-described cross processed marks, That is, the center coordinates that are position data are detected (step S105), and the data is stored in the storage unit 12g.

If it is determined in step S104 that the number of mark scans is greater than or equal to the maximum mark scan value, the mark scan position of the FIB is shifted to a predetermined position (step S106), and the number of mark scans is reset. (Step S107), the process by the above-mentioned step S105 is performed.

Next, when the center coordinates of the mark are obtained in step S105, the central processing unit 12k increments the number of mark scans (step S108).
It is determined whether or not the obtained center coordinates of the mark are the initially obtained data (step S109).

When the center coordinates of the mark are the first-obtained data, the processing from step S104 is performed.

If the center coordinates of the mark obtained in step S105 are data obtained after the second time,
The data comparing unit 12i compares the initially obtained center coordinates of the mark, that is, the data stored in the storage unit 12g with the latest data obtained in step S105, and determines whether the center coordinates of the marks are the same. A judgment is made (step S110).

Next, in the processing of step S110,
If the compared data are the same, the central processing unit 12k adds a predetermined correction time to the mark scan interval time input in step S102 (step S102).
111), the interval time is set again to be long, and the processing from step S104 is performed again.

Further, in the processing of step S110,
When the compared data are different, that is, when the sample is moving, the central processing unit 12k calculates the deviation amount of the compared data, and outputs the calculation result to the scan controller 12d, and the FIB is calculated by the deviation amount. The machining position is corrected by shifting (step S11).
2).

If the calculated data shift amount exceeds the preset shift amount, step S10 is performed.
In step 2, the predetermined correction time is subtracted from the input interval time, and the interval time is set short again. If the calculated data shift amount is smaller than the preset shift amount, the above-mentioned interval time is set. The processing from step S104 is performed again while setting the same time (step S113).

Now, a method of detecting the positional deviation of the center coordinates of the mark M will be described with reference to FIGS. 4 (a) and 4 (b).

In this case, as shown in FIGS. 4A and 4B, it is assumed that the center of the mark M is moved from the position D1 to the position D2.

First, in the line scanning by the FIB for obtaining the brightness modulation signal on the X axis, scanning is performed in the range of positions Da to Dd in the X (horizontal) direction with respect to the plane of the sample, and also on the Y axis. The line scan by the FIB for obtaining the brightness modulation signal is performed in the range of positions De to Dh in the Y (longitudinal) direction with respect to the plane of the sample.

Then, the signal obtained by the line scan in the range of the positions Da to Dd and the range of the positions De to Dh is converted into the brightness modulation signal by the detector 8.

These luminance modulation signals are processed by the waveform processing unit 12
i (FIG. 1), the waveform is converted into the X-direction waveform XH and the Y-direction waveform YH.

Next, with respect to the waveform XH and the waveform YH converted by the waveform processing unit 12i, the central processing unit 12k detects coordinate data at a position D1 of the cross-shaped mark M, that is, a portion having a large contrast.

The position data in the X direction of the mark M detected thereby is the position Db, the position data in the Y direction is the position Df, and these position data are stored in the storage section 12g.

Thereafter, a second line scan by FIB is similarly performed in the range of positions Da to Dd in the X (horizontal) direction with respect to the plane of the sample, and at the position D in the Y (longitudinal) direction.
It is performed in the range of e to Dh, and the detector 8 converts the luminance modulation signal.

Similarly, the waveform processing unit 12i performs conversion into the X-direction waveform XH and the Y-direction waveform YH, and the X-direction position data and the Y-direction position data of the mark M are detected.

Since the sample has moved from the position D1 to the position D2, the position data detected after the sample has moved is the position Dc in the X direction and the position Dg in the Y direction.

Next, the calculation unit 12j subtracts the position Dc which is the second detected position data in the X direction from the position Db in the X direction stored in the storage unit 12g, and the result is stored in the central processing unit. Output to 12k.

Similarly, the arithmetic unit 12j has the storage unit 1
The position Dc, which is the Y-direction position data detected for the second time, is subtracted from the Y-direction position Db stored in 2g, and the result is output to the central processing unit 12k.

Then, based on the input data, the central processing unit 12k detects the deviation amount of the mark M in the X direction and the deviation amount of the mark M in the X direction.

In the line scanning by the FIB at this time, the mark scanning position by the FIB is shifted when the number of times of scanning reaches a predetermined number or more in the processing of step S106 described above, and it is processed by the line scanning of FIB. By minimizing the damage to the sample such as the edge of the mark M being scraped, the positional accuracy of the mark M is prevented from being deteriorated.

Further, if the compared position data are the same, the FIB can also be set by resetting the line scan interval time longer by the processing of step S111.
The damage to the sample due to the line scan is reduced, and the position accuracy is prevented from being degraded by the edge scan of the mark M due to the FIB line scan.

Accordingly, in the present embodiment, the FIB controller 12 automatically corrects the irradiation area of the FIB by electrically shifting it when the sample is processed, so that even if the sample or the stage 9 moves. FI with high accuracy
B processing can be performed.

Although the invention made by the present inventor has been specifically described based on the embodiments of the present invention, the present invention is not limited to the above embodiments, and various modifications can be made without departing from the scope of the invention. It goes without saying that it can be changed.

For example, in the above-described embodiment, the cross-shaped mark is formed at a predetermined position of the sample by the FIB processing. However, it is sufficient that the mark can recognize the position. The mark may be formed.

[0076]

Advantageous effects obtained by typical ones of the inventions disclosed by the present application will be briefly described as follows.
It is as follows.

(1) According to the present invention, even if the processing position of the focused ion beam irradiating the sample during processing is deviated, the processing position is automatically corrected, so that highly accurate processing can be performed.

(2) Further, in the present invention, since the mark is formed by irradiating the sample to be processed with the focused ion beam, it is possible to easily form a mark which serves as a mark for recognizing the processing position.

(3) Further, in the present invention, the line scan interval time and the line scan position are shifted according to the deviation amount of the processing position and the number of line scans. Can be processed with high precision.

(4) Further, according to the present invention, the above (1)
From (3) to (3), it is possible to eliminate processing defects such as disappearance of the observation part and insufficient processing in the cross-section processing of the sample, and it is possible to improve the processing yield in the focused ion beam apparatus.

[Brief description of drawings]

FIG. 1 is a structural explanatory view of a focused ion beam device according to an embodiment of the present invention.

FIG. 2 is a block diagram of a control circuit of a focused ion beam device according to an embodiment of the present invention.

FIG. 3 is a control flowchart of the focused ion beam device according to the embodiment of the present invention.

4 (a) and 4 (b) are explanatory views of a method for detecting positional deviation of the center coordinates of marks formed on a sample according to an embodiment of the present invention.

[Explanation of symbols]

1 Focused Ion Beam Device 2 Chamber 3 Gallium Metal Ion Source (Ion Beam Source) 4 First Electrostatic Lens 5 Aperture 6 Second Electrostatic Lens 7 Scanning Coil 8 Detector (Brightness Modulating Means) 9 Stage 10 Turbo Pump 11 Rotary Pump 12 FIB controller 12a Input device (input means) 12b Ion source controller 12c Lens controller 12d Scan controller (ion beam control means) 12e Stage controller 12f Exhaust system controller 12g Storage unit (storage unit) 12h Waveform processing unit (waveform processing unit) 12i Data comparison unit (data comparison unit) 12j Calculation unit (calculation unit) 12k Central processing unit (first and second control unit) 13 Display unit M mark D1 position D2 position Da to Dh position XH waveform YH waveform

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yu Sekihara 5-20-1 Kamimizuhoncho, Kodaira-shi, Tokyo Inside Hiritsu Cho-LS Engineering Co., Ltd. (72) Inventor Kazumasa Yoshinaga Tokyo 5-20-1 Kamimizuhoncho, Kodaira-shi Hirate Super L.S.I Engineering Co., Ltd. (72) Inventor Takao Shishido 5-20-1 Kamimizuhoncho, Kodaira-shi, Tokyo Hirate RLS・ I Engineering Co., Ltd. (72) Inventor Kaoru Osayonani 2326 Imai, Ome-shi, Tokyo Hitachi, Ltd. Device Development Center

Claims (6)

[Claims] 1. A step of detecting a position of a predetermined mark by a line scan of a focused ion beam at predetermined intervals, a position of the mark detected first and a position of the mark detected most recently. Comparing, the step of calculating the amount of deviation between the position of the first detected mark and the latest detected mark, and shifting the focused ion beam during irradiation based on the calculated amount of deviation, the processing position And a step of correcting. 2. The control method according to claim 1, wherein the mark is formed by irradiating a sample to be processed with a focused ion beam. 3. The control method according to claim 1 or 2, wherein the step of comparing the deviation amount obtained in the step of calculating the deviation amount with a preset deviation amount, and the calculated deviation amount being set. If the deviation amount is larger than the calculated deviation amount, the correction time of a predetermined time is subtracted from the interval time to shorten the interval time, and if there is no difference between the calculated deviation amount and the set deviation amount, A step of adding a correction time to extend the interval time. 4. The control method according to claim 1, wherein the number of line scans in the step of detecting the position of the predetermined mark is compared with a preset number of times, and the number of line scans is compared. The control method is characterized in that it has a step of shifting the line scan position by the focused ion beam when the number of times exceeds a preset number. 5. A focused ion beam apparatus for irradiating a sample with a focused ion beam to perform fine processing, comprising: input means for inputting an interval time for detecting the position of a predetermined mark on the sample; and the input means. Mark detection means for detecting the position of the mark by the line scan of the focused ion beam at every input predetermined interval time, and the amount of deviation between the position of the mark detected first and the position of the latest detected mark. The focused ion beam apparatus is provided with position correction means for correcting the processing position by shifting the focused ion beam during irradiation based on the above. 6. The focused ion beam apparatus according to claim 5, wherein the mark detecting means emits an ion beam for irradiating the mark on the surface of the sample to the mark at every predetermined interval time input by the input means from an ion beam source. Ion beam control means for generating, brightness modulation means for detecting secondary electrons and secondary ions emitted by the irradiation of the ion beam controlled by the ion beam control means and converting them into a brightness modulation signal, and the brightness. Waveform processing means for converting the luminance modulation signal converted by the modulation means into a waveform signal,
The position correction is composed of first control means for detecting the position data of the mark converted by the waveform processing means, and storage means for storing the position data first detected by the first control means. A means for comparing the position data of the mark stored in the storage means with the position data of the mark most recently detected by the mark detecting means, and based on the comparison result of the data comparing means. A calculation unit that calculates a deviation amount between the position of the mark detected first and the latest detected mark, and shifts the focused ion beam during irradiation based on the deviation amount calculated by the calculation unit, A focused ion beam device comprising a second control means for correcting the processing position.