JP2001015570A - Fib processing method and positioning method for fib processing position - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform more highly accurate cross section processing by determining predetermined positions on an FIB (focused ion beam) image than in conventional methods. SOLUTION: A predetermined position 2 of a semiconductor sample 1 is observed using an optical microscope, and a number of lines of deposition film 5 such as a silicon oxide film that transmits light directly to the position 2 are formed based on the observed image. The position 2 is observed together with the film 5 using the optical microscope again. Since the film 5 transmits light, the position 2 can be located either on one of the lines of the film 5 or a space between the lines of the film 5. Thus, FIB-based cross section processing is performed while targeting such line or space where the position 2 is located.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a FIB (Focused
FIB when performing cross-section processing by FIB by positioning a specific location that cannot be observed from the surface in the image (Ion Beam)
The present invention relates to a processing method and an FIB processing position positioning method.

[0002]

2. Description of the Related Art Conventionally, a defective portion on a semiconductor chip is specified and a cross section is processed by FIB.
Observation of the defective part is performed. 18 to 21 are views showing a method of processing a FIB cross section according to a conventional technique.

FIG. 18 is an image obtained by observing a specific portion 2 such as a failed portion in the semiconductor sample 1 with an optical microscope or a laser microscope. Based on this image, the FIB shown in FIG.
As shown in the image, a plurality of tungsten or platinum films that do not transmit light are deposited as a deposition film 3 by FIB in the vicinity of the specific portion 2 for marking. At this time, the specific portion 2 cannot be observed in the FIB image.

[0006] Next, as shown in FIG. 20, the specific portion 2 is again observed together with the deposition film 3 using an optical microscope or a laser microscope. Then, the distance from the deposition film 3 to the specific portion 2 is measured on this image, and the section processing position 4 is determined based on the measured value on the FIB image as shown in FIG. I do.

[0005]

SUMMARY OF THE INVENTION The above conventional F
According to the method of processing a semiconductor sample by IB, (1)
The specific location 2 and the deposition film 3 are observed with an optical microscope or a laser microscope, and the distance from the deposition film 3 to the specific location 2 is measured from the image. However, since the resolution is poor, a measurement error occurs, and the FIB In this case, there is a problem that the cross-section processing position 4 deviates from the specific location 2 and the accuracy of the cross-section processing deteriorates.

(2) When depositing a plurality of tungsten or platinum deposition films 3 in the vicinity of the specific location 2 by FIB, if the deposition film 3 is erroneously deposited on the specific location 2, then the optical microscope or Since the specific portion 2 cannot be observed with the laser microscope, the cross-section processing position 4 cannot be specified, and there has been a problem that the cross-section processing cannot be performed.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional problems, and an object of the present invention is to determine the position of a specific portion on an FIB image more accurately and more reliably than in the past. An object of the present invention is to provide a FIB processing method and a method of positioning a FIB processing position, which can perform high-precision cross-section processing without any problem.

[0008]

In order to achieve the above object, a feature of the present invention is that an FIB which determines a processing position when a cross section is processed by a FIB at a specific portion of a semiconductor sample which cannot be visually recognized in a FIB image. In the positioning method of the processing position, based on the relative positional relationship between the striped deposition film transmitting light formed in the region including immediately above the specific location of the semiconductor sample and the specific location,
It is to determine a cross-section processing position of the specific portion.

According to a second aspect of the present invention, there is provided an FIB processing position locating method for determining a processing position when a cross section is processed by a FIB at a specific location of a semiconductor sample which cannot be visually recognized in an FIB image. 2 formed on both sides without covering this particular location
A cross-sectional processing position of the specific portion is determined based on a relative positional relationship between the striped deposition film at the portion and the specific portion.

According to a third aspect of the present invention, in a FIB processing method for processing a cross-section of a specific portion of a semiconductor sample that cannot be visually recognized in an FIB image by FIB, an area including a portion immediately above the specific portion of the semiconductor sample has a stripe shape. A step of forming a deposition film that transmits light by FIB; and a step of determining a relative positional relationship between the deposition film that transmits the striped light and the specific portion using an optical microscope or a laser microscope. Determining, on the FIB image, the striped deposition film or a cross-sectional processing position between the striped deposition films based on the determined relative positional relationship between the striped deposition film and the specific portion. To include.

According to a fourth aspect of the present invention, there is provided an FIB processing method for processing a cross-section of a specific portion of a semiconductor sample which cannot be visually recognized in an FIB image by FIB, in a region including immediately above the specific portion of the semiconductor sample. Forming a light-transmitting deposition film by FIB;
Using a MS or OBIC to cause the specific location to emit light by electrical leakage, and determine a relative positional relationship between the deposition film transmitting the striped light and the emitted specific location; and F based on the relative positional relationship between the striped deposition film and the specific location.
Determining the striped deposition film or a cross-section processing position therebetween on the IB image.

According to a fifth aspect of the present invention, in a FIB processing method for processing a cross-section of a specific portion of a semiconductor sample that cannot be visually recognized in an FIB image by FIB, the specific portion is covered on both sides of the specific portion of the semiconductor sample. Forming a striped deposition film at two locations by FIB without using FIB; creating a brightness graph of the striped deposition film at the specific location and the two locations using EMS or OBIC; A step of determining the relative positional relationship between the striped deposition film and the specific location, and based on the determined relative positional relationship between the striped deposition film and the specific location, Determining the striped deposition film or a cross-sectional processing position between the deposition films on the FIB image.

A feature of the invention according to claim 6 is that, before forming the striped deposition film, a deposition film is formed at a plurality of locations around the specific location, and the deposition films at the plurality of locations are formed. After determining the relative position between the target and the specific portion, the striped deposition film is formed based on the relative position.

[0014]

Embodiments of the present invention will be described below with reference to the drawings. 1 to 4 are explanatory views showing a first embodiment of the FIB processing method and the FIB processing position positioning method of the present invention. FIG. 1 is a plan view showing an example of observation of a specific portion by an optical microscope or a laser microscope, FIG. 2 is a plan view showing an example of deposition film deposition on an FIB screen, and FIG. FIG. 4 is a plan view showing an example of observation of a deposition film by FIB and an example of processing positioning.

FIG. 1 is an image obtained by observing a specific portion 2 in a semiconductor sample 1 with an optical microscope or a laser microscope. Based on this image, as shown in the FIB image of FIG. 2, a deposition film 5 such as a carbon or silicon oxide film that transmits light is applied by FIB in the form of horizontal stripes (line and space) just above the specific portion 2 to perform marking. I do. The interval between the deposition films 5 in the form of horizontal stripes is, for example, 0.5 μm.
m.

Next, as shown in FIG. 3, the specific portion 2 is again observed together with the deposition film 5 with an optical microscope or a laser microscope. At this time, since the deposition film 5 transmits light, the specific portion 2 is observed in the line-shaped deposition film 5.

Then, on this image, it is confirmed in which line or space the specific portion 2 is located on the horizontal striped deposition film 5. Thereafter, on the FIB image shown in FIG. 4, cross-section processing by FIB is performed by aiming at the line or space of the deposition film 5 where the confirmed specific portion 2 is located, to obtain a cross-section processed portion 6.

According to the present embodiment, the horizontal stripe-shaped transparent deposition film 5 is attached to the region directly above the specific portion 2, and the relative positional relationship between the specific portion 2 and the deposition film 5 can be determined with an optical microscope or a microscope. By confirming with a laser microscope, the line of the deposition film 5 where the specific portion 2 is located or the interval between the lines can be determined more accurately and more reliably than in the past.
The IB enables highly accurate cross-section processing of the specific portion 2 without failure.

Further, since the line or space where the specific portion 2 is located can be observed with the FIB and the cross section can be processed by the FIB on the image, there is no need to transfer the semiconductor sample 1 and a processing error due to a positional shift or the like. And processing can be performed with a simple process.

FIGS. 5 to 8 are explanatory views showing a second embodiment of the FIB processing method and the FIB processing position positioning method according to the present invention. FIG. 5 is a plan view showing an example of observation of a light emitting portion due to electric leakage of EMS or OBIC, FIG. 6 is a plan view showing an example of deposition film deposition on an FIB screen, and FIG. 7 is electric leakage of EMS or OBIC. FIG. 8 is a plan view showing an example of the observation of the deposition film and the processing positioning by FIB.

In this embodiment, instead of an optical microscope or a laser microscope, an optical microscope is equipped with a device for emitting light at a specific portion of a sample by electric leak, or a laser microscope is used to emit light at a specific portion of a sample by electric leak. Where the OBIC with the device to make
This is different from the first embodiment described above.

FIG. 5 is an image obtained by observing a specific portion 2 which emits light by electric leak in the semiconductor sample 1 by EMS or OBIC. Based on this image, as shown in the FIB image of FIG. 6, a deposition film 5 such as a carbon or silicon oxide film that transmits light by FIB is provided in a line shape immediately above the specific portion 2 that emits light.

Next, as shown in FIG.
The specific portion 2 that emits light again at C is observed together with the deposition film 5. At this time, since the deposition film 5 transmits light, a light emitting portion is observed in the deposition film 5 provided in a line shape. And the specific spot 2 that emits light on this image
Is located on which line or space of the deposition film.

Then, on the FIB image shown in FIG.
The cross-section processing is performed to obtain the cross-section processed portion 6.

According to the present embodiment, EMS or OB
Using the IC to emit light at the specific portion 2, confirming its position and attaching the deposition film 5, and then confirming the relative positional relationship between the specific portion 2 and the deposition film 5 that emit light. Therefore, the visibility is improved, and accordingly, the position of the specific portion 2 can be determined more accurately and surely, and the FIB can perform more accurate cross-sectional processing of the specific portion 2 without failure.

FIG. 9 to FIG. 12 are explanatory views showing a third embodiment of the FIB processing method and the FIB processing position positioning method according to the present invention. FIG. 9 is a plan view showing an example of observation of a specific portion by an optical microscope or a laser microscope, and FIG. 10 is an optical microscope or a laser microscope.
And FIG. 11 is a plan view showing an example of re-observing a specific portion.
FIG. 12 is a plan view showing an example of re-observing a specific part and FIG. 12 is a plan view showing an example of observation of a deposition film by FIB and processing positioning.

FIG. 9 is an image obtained by observing a specific portion 2 in the semiconductor sample 1 by EMS or OBIC. Based on this image, as shown in the FIB image of FIG.
A plurality of tungsten or platinum films which do not transmit light are attached as FIB deposition films (marking) 3 as markings. At this time, the specific location 2 is F
It cannot be observed in the IB image.

Next, on the FIB image, a deposition film 5 such as a carbon or silicon oxide film which transmits light by the FIB is formed in a line shape just above the almost specific portion 2 determined by the marking 3.

Next, as shown in FIG.
The specific portion 2 emitting light from the IC is observed together with the deposition film 5. At this time, since the horizontal stripe-shaped deposition film 5 transmits light, the deposition film 5 or the specific portion 2 emitting light therebetween is observed.

Then, it is confirmed which line or space of the deposition film 5 has the specific portion 2 which emits light on this image.

After that, on the FIB image shown in FIG. 12, a section processing by FIB is performed by aiming at a corresponding line or space of the deposition film 5 to obtain a section processing section 6.

According to the present embodiment, when the specific portion 2 is very small, first, a plurality of deposition films 3 are attached at positions surrounding the specific portion 2, and the specific portion 2 is formed based on these deposition films 3. By specifying the approximate position, even if the specific portion 2 is minute, the line- or space-like deposition film 5 can be accurately applied directly above the specific portion 2, and the second portion shown in FIG. The same effect as that of the embodiment can be obtained.

In this embodiment, EMS or OB
Although the IC is used, the same effect can be obtained without causing the specific portion 2 to emit light using an optical microscope or a laser microscope.

FIGS. 13 to 17 are explanatory views showing a fourth embodiment of the FIB processing method and the FIB processing position positioning method according to the present invention. Figure 13 is EMS or OBIC
Plan view showing an example of observation of a light emitting portion due to electrical leakage of
FIG. 14 is a plan view showing a marking shape of a deposition film disposed around a specific portion, FIG. 15 is a luminance measurement graph measuring the luminance of the specific portion and the stripe-shaped marking, and FIG.
FIG. 17 is a plan view showing an example of one-side cross-section processing shape after observing the deposition film in FIB and processing positioning, and FIG.
It is the top view which showed the example of the both-sides cross-section processing shape after observing the deposition film in B and processing positioning.

In FIG. 13, a specific portion 2 in the semiconductor sample 1 is observed by EMS or OBIC. Based on this image, as shown in a FIB image of FIG. Marking 13 is performed by FIB by depositing a tungsten or platinum film which does not transmit.

Thereafter, the position of the specific portion 2 which emits light is identified by the EMS or OBIC using the marking 13 as a mark, and the horizontal stripes formed of the deposition film by FIB on both sides of the finally identified location are used. The marking 14 is performed.

The markings 14 are applied to both sides of the specific portion 2 without covering them, and the markings 14 are attached so that straight lines connecting opposing lines on both sides are parallel to each other. Marking 14 in this case
May be opaque, such as tungsten, or may be transparent, such as a silicon oxide film.

Thereafter, the luminance 15 of the specified portion 2 and the luminance 16 of the markings 14 on both sides specified by using EMS or OBIC are measured, and a luminance graph 17 is created as shown in FIG. In this brightness graph 17, the brightness 15 of the specific portion 12 and the brightness 1 of the markings 14 on both sides are shown.
6 is observed, and the relative position between the specific portion 2 and the marking 14 is determined, and the cross-section processing portion is positioned.

After that, as shown in FIG. 16, one side of the specific portion 2 is cross-sectioned by FIB to obtain a one-side processed shape 18, which is then observed and analyzed by SEM (Scanning Electron Microscopy) to obtain a specific portion. The detailed observation 2 is performed.

Alternatively, as shown in FIG.
After processing both sides of FIB with FIB, TEM (Transm
By observing and analyzing with an ission electron microscope, it is also possible to observe a fine shape with high spatial resolution.

According to the present embodiment, after the striped markings 14 are attached to both sides of the specific portion 12, a brightness graph 17 of the striped marking 14 and the specific portion 2 is created. Since the relative positional relationship between the specific portion 2 and the markings 14 is determined based on this, the position of the specific portion 2 can be specified with extremely high accuracy, and the specific portion 2 can be positioned with high accuracy.

Further, if the semiconductor sample 1 is processed by the FIB, the parallel marking of the line-shaped markings 14 can be easily performed.
A double-sided processed shape 19 can be obtained. Therefore, the TEM
As a result, the success rate of the direct analysis of the failure location can be improved, and the time required for re-execution can be reduced.

Therefore, by processing both sides of the semiconductor sample 1 by FIB, and observing and analyzing by TEM,
Observation and analysis of fine shapes with high spatial resolution are possible,
Analysis can be performed even on a minute specific portion 2 that cannot be analyzed by EM or FIB. In order to perform this TEM observation, the sample must be made thinner, and the specification of the processed portion is a very important factor, and the above-described method can exhibit remarkably usefulness.

Further, since the stripe-shaped markings 14 are provided on both sides of the specified portion 12, even if the markings 14 are an opaque deposition film such as a tungsten film or a platinum film, the above effect can be obtained.

[0045]

As described above in detail, according to the first to third aspects of the present invention, the position of a specific location on the FIB image is determined by the relative positional relationship between the striped deposition film and the specific location. Therefore, the cross-section processing position can be determined more accurately and more reliably than in the past, and the cross-section processing with higher accuracy can be performed.

According to the fourth aspect of the present invention, since the specific portion emits light, the visibility is improved, and the relative positional relationship between the striped deposition film and the specific portion can be accurately known. The position of the specific portion on the image can be determined more accurately and reliably, and highly accurate cross-section processing can be performed.

According to the fifth aspect of the present invention, since the relative position relationship between the striped deposition film and the specific portion can be known with high accuracy because the luminance graph is used, the processing position can be determined with high accuracy. High-accuracy cross-section processing can be performed.

According to the sixth aspect of the present invention, a deposition film is attached to a plurality of locations around a specific location, and the approximate position of the specific location is determined based on the deposition film. Is attached directly above or on both sides of a specific location, so that even if the specific location is very fine, the striped deposition film can be attached to a predetermined position. Therefore, it is necessary to accurately and accurately determine the cross-section processing position on the FIB image. This makes it possible to perform high-precision cross-section processing even when a specific portion is minute.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing a first embodiment of an FIB processing method and a method of positioning an FIB processing position according to the present invention, and is a plan view showing an example of observing a specific portion with an optical microscope or a laser microscope.

FIG. 2 is an explanatory view showing a first embodiment of the FIB processing method and the FIB processing position positioning method of the present invention, and is a plan view showing an example of deposition film formation on a FIB image.

FIG. 3 is an explanatory view showing a first embodiment of the FIB processing method and the FIB processing position positioning method of the present invention, and is a plan view showing an example of re-observation of a specific portion of an optical microscope or a laser microscope. .

FIG. 4 is an explanatory view showing a first embodiment of the FIB processing method and the FIB processing position positioning method according to the present invention, and is a plan view showing an example of observation of a deposition film and processing positioning in the FIB. is there.

FIG. 5 is an explanatory view showing a second embodiment of the FIB processing method and the FIB processing position positioning method according to the present invention, and is a plan view showing an example of observing a light emitting portion due to electric leakage of EMS or OBIC. is there.

FIG. 6 is an explanatory view showing a second embodiment of the FIB processing method and the FIB processing position positioning method of the present invention, and is a plan view showing an example of deposition film deposition on the FIB screen.

FIG. 7 is an explanatory view showing a second embodiment of the FIB processing method and the FIB processing position positioning method according to the present invention, and is a plan view showing an example of re-observation of a light emitting portion due to electric leakage of EMS or OBIC. It is.

FIG. 8 is an explanatory view showing a second embodiment of the FIB processing method and the FIB processing position positioning method according to the present invention, and is a plan view showing an example of observation of a deposition film and processing positioning in the FIB. is there.

FIG. 9 is an explanatory view showing a third embodiment of the FIB processing method and the FIB processing position positioning method according to the present invention, and is a plan view showing an example of observing a specific portion with an optical microscope or a laser microscope.

FIG. 10 is an explanatory view showing a third embodiment of the FIB processing method and the FIB processing position positioning method of the present invention, wherein the deposition film 3 and a specific portion are re-observed with an optical microscope or a laser microscope. It is the top view which showed the example.

FIG. 11 is an explanatory view showing a third embodiment of the FIB processing method and the FIB processing position positioning method according to the present invention, wherein the deposition films 3, 5 and a specific portion are re-used by an optical microscope or a laser microscope. It is the top view which showed the example observed.

FIG. 12 is an explanatory view showing a third embodiment of the FIB processing method and the FIB processing position positioning method of the present invention, and is a plan view showing an example of observation of a deposition film by FIB and processing positioning. .

FIG. 13 is an explanatory view showing a fourth embodiment of the FIB processing method and the FIB processing position positioning method of the present invention, and is a plan view showing an example of observing a light emitting portion due to electric leakage of EMS or OBIC. is there.

FIG. 14 is an explanatory view showing a fourth embodiment of the FIB processing method and the FIB processing position positioning method of the present invention, and is a plan view showing a marking shape arranged around a specific location.

FIG. 15 is an explanatory diagram showing a fourth embodiment of the FIB processing method and the FIB processing position positioning method according to the present invention, and is a luminance measurement graph diagram in which the luminance of a specific portion and the stripe-shaped marking is measured. .

FIG. 16 is an explanatory view showing a fourth embodiment of the FIB processing method and the FIB processing position positioning method according to the present invention, in which a one-side cross-section processing shape after observation of a deposition film and processing positioning in the FIB; It is the top view which showed the example.

FIG. 17 is an explanatory view showing a fourth embodiment of the FIB processing method and the FIB processing position positioning method according to the present invention, and shows the both-side cross-sectional processing shape after the FIB observation of the deposition film and the processing positioning. It is the top view which showed the example.

FIG. 18 is a diagram showing a cross-section processing method of an FIB cross-section according to a conventional technique, and is a plan view showing an example of observing a specific portion with an optical microscope or a laser microscope.

FIG. 19 is a diagram showing a cross-section processing method of a FIB cross-section according to a conventional technique, and is a plan view showing an example of depositing a deposition film on an FIB screen.

FIG. 20 is a view showing a cross-section processing method of an FIB cross-section according to a conventional technique, and is a plan view showing an example of re-observation of a specific portion with an optical microscope or a laser microscope.

FIG. 21 is a view showing a cross-section processing method of an FIB cross-section according to a conventional technique, and is a plan view showing an example of deposition film observation and processing positioning in the FIB.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Semiconductor sample 2 Specific place 3, 5 Deposition film 6 Cross-section processing part 13, 14 Marking 15, 16 Brightness 17 Brightness graph 18 One-side processing shape 19 Both-side processing shape

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) // G01R 1/06 H01L 21/302 D 9A001 31/302 G01R 31/28 L (72) Inventor Tomoko Tanaka 25-1, Ekimae Honmachi, Kawasaki-ku, Kawasaki-ku, Kanagawa Prefecture, Japan Toshiba Microelectronics Co., Ltd. 25-1, Ekimae-Honmachi, Kawasaki-ku, Kawasaki-ku, Japan F term (reference) 2G011 AB00 AC00 AE00 2G032 AA00 AB20 AF07 AL00 4M106 AA02 BA03 BA12 CA50 CA51 DH50 DH60 DJ38 5C034 DD09 5F004 AA16 EB08 FA08 9A48 KK05 LL05

Claims (6)

[Claims] 1. A method of positioning a FIB processing position for determining a processing position when a cross-section is processed by a FIB at a specific portion of a semiconductor sample that cannot be visually recognized in an FIB image. A cross-section processing position of the specific location is determined based on a relative positional relationship between the striped deposition film transmitting the light and the specific location. 2. A FIB processing position positioning method for determining a processing position when a cross-section is processed by a FIB at a specific portion of a semiconductor sample which cannot be visually recognized in an FIB image, wherein the specific portion is provided on both sides of the specific portion of the semiconductor sample. FIB, wherein a cross-sectional processing position of the specific portion is determined based on a relative positional relationship between the two striped deposition films formed without covering and the specific portion.
Positioning method of processing position. 3. An FIB for processing a specific portion of a semiconductor sample, which cannot be visually recognized in an FIB image, by FIB.
In the processing method, a step of forming, by FIB, a deposition film that transmits striped light in a region including immediately above a specific portion of the semiconductor sample, and transmitting the striped light using an optical microscope or a laser microscope. A step of determining a relative positional relationship between the deposition film and the specific location; and, on the FIB image, based on the determined relative positional relationship between the striped deposition film and the specific location. A step of determining the striped deposition film or a cross-section processing position therebetween. 4. An FIB for processing a specific portion of a semiconductor sample, which cannot be visually recognized in the FIB image, by FIB.
In the processing method, a step of forming, by FIB, a deposition film that transmits striped light in a region including immediately above a specific portion of the semiconductor sample, and causing the specific portion to emit light by electric leak using EMS or OBIC. Determining a relative positional relationship between the deposition film that transmits the striped light and the emitted specific portion; and a relative position between the determined striped deposition film and the specific portion. Determining the striped deposition film or a cross-section processing position between the striped deposition films on the FIB image based on a proper positional relationship. 5. An FIB for processing a specific portion of a semiconductor sample, which cannot be visually recognized in an FIB image, by FIB.
In the processing method, a striped deposition film is formed on both sides of a specific portion of the semiconductor sample by FIB without covering the specific portion.
A step of forming a spot; a step of creating a luminance graph of the striped deposition film at the specific spot and the two spots using EMS or OBIC; and a step of forming the striped deposition film and the specific spot by the brightness graph. Determining the relative positional relationship between the striped deposition film and the specific location on the FIB image based on the determined relative positional relationship between the striped deposition film and the specific portion. Determining a cross-section processing position between them, and a FIB processing method. 6. A deposition film is formed at a plurality of locations around the specific location before forming the striped deposition film, and a relative position between the deposition films at the plurality of locations and the specific location is defined. 6. The FIB processing method according to claim 3, wherein, after the position is determined, the striped deposition film is formed based on the relative position.