JPH08313415A - Sample production method of transmission electron microscope and converged ion beam processing apparatus - Google Patents

Abstract

PURPOSE: To simply slide a section observing sample up to observable thickness within a short time. CONSTITUTION: Raw material gas W(CO)6 is ejected on the surface of the section observing samaple 8 at the section observing place 11 and the peripheral part thereof observed by a transmission type electron microscope from the gap jet nozzle 3 of a converged ion beam processing apparatus 1 and decomposed by the Ga<+> ion beam 4 emitted from an ion gun 5 using Ga as ion seeds to selectively deposit W to form a W vapor deposition film. Sputtering etching using Ar as ion seeds is applied to the surface of the sample 8 containing the W vapor deposition film to selectively leave the section observing place under the W vapor deposition film and the peripheral part thereof and the section observing place 11 is sliced by fine processing using Ga ions to produce a section observing sample.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for preparing a sample to be observed with a transmission electron microscope and a processing apparatus for preparing the sample.

[0002]

2. Description of the Related Art In recent years, with the miniaturization of semiconductor device patterns, the importance of a technique for observing and evaluating a specific minute portion with a transmission electron microscope (hereinafter abbreviated as TEM) is increasing. However, in order to observe the specific minute portion by TEM, the specific minute portion must be thinned to a thickness of 0.3 μm or less, which is extremely difficult to manufacture.

Therefore, conventionally, as a method for solving this problem, a sample for cross-section observation is prepared by a focused ion beam (hereinafter abbreviated as FIB) processing apparatus, and a specific minute portion is TEM.
A method of observation has been reported (Hata et al., "Analysis of Aluminum Wiring by Transmission Electron Microscope", IEICE Technical Report SDM90).
-, 4 (1990)).

A method of preparing a sample for cross-section observation using the above-mentioned conventional FIB processing apparatus will be described below with reference to the drawings. 8 to 11 show a cross-section observation sample preparation method using an FIB processing apparatus, and FIG.
A perspective view is shown in which a sample prepared using a FIB processing apparatus is arranged for EM observation. As shown in FIG. 8, on a silicon (hereinafter abbreviated as Si) substrate 20,
A semiconductor device pattern 21 is formed, and
On this semiconductor device pattern 21, cross-section observation points 22 to be observed by TEM are marked. First, as shown in FIG. 9, the Si substrate 20 thus configured is
By cutting and mechanical polishing, a size of 0.2 × 3 mm centering on the cross-section observation point 22 is processed. And then, as shown in FIG.
As shown in FIG. 0, as rough processing before FIB processing, the semiconductor device pattern 21 in the peripheral portion of the cross section observation spot 22 is removed by laser light (not shown), and the cross section observation spot 22 is removed.
The peripheral region 23 is formed. Further, as shown in FIG. 11, the pole peripheral portion of the cross section observation spot 22 is removed by a Ga ⁺ ion beam (not shown) of the FIB processing apparatus to form the pole peripheral portion region 24 of the cross section observation spot 22. In addition,
Semiconductor device pattern 2 around the cross-section observation point 22
The reason that 1 is removed by laser light is to narrow the processing region by the Ga ⁺ ion beam and shorten the sample preparation time.

As described above, the sample produced by the above method is
As shown in FIG. 12, the sample is placed in a state where a cross-section can be observed by a TEM, and a transmission electron beam 25 is emitted from an electron gun of the TEM to a cross-section observation portion 22 of this sample, and the sample is observed.

[0006]

However, in the above-mentioned method for preparing a sample for cross-section observation, a large amount of time is required because the semiconductor device pattern 21 in the peripheral portion of the cross-section observation spot 22 is roughly processed by laser light. In addition, there is a risk that the laser light may destroy the TEM observation spot 22.

An object of the present invention is to provide a sample preparation method and a processing apparatus capable of easily and thinly slicing a cross-section observation sample up to an observable thickness in a short time.

[0008]

A sample preparation method for a transmission electron microscope and a focused ion beam processing apparatus according to the present invention include:
A W vapor deposition film was formed on the sample surface at the cross-section observation site and its periphery by a FIB processing device in a shape corresponding to the size of the cross-section observation site, and Ar was used as an ion species on the sample surface including the W vapor deposition film. By performing sputter etching, W
It is characterized in that the cross-section observation area under the vapor deposition film and its peripheral area are selectively left.

Further, the sample preparation method for the transmission electron microscope and the focused ion beam processing apparatus of the present invention are an ion gun using Ga as an ion species capable of forming a W deposition film and sputter etching of a minute region in the FIB processing apparatus. In addition to Ar, which can perform sputter etching at high speed and in a wide range
It is characterized in that an ion gun with an ion species of 1 is provided, and two types of sputter etching can be performed at the same time.

[0010]

The method of preparing a sample for a transmission electron microscope and the focused ion beam processing apparatus of the present invention include a W vapor deposition film formed by the FIB processing apparatus by sputter etching using Ar as an ion species, and a cross-section observation point thereunder. The peripheral part including the part is selectively left with high accuracy and high speed.

Further, the focused ion beam processing apparatus of the transmission electron microscope of the present invention uses Ga ions by providing an ion gun using Ga as an ion species and an ion gun using Ar as an ion species in the FIB processing apparatus. Fine processing and rough processing with Ar ions can be performed simultaneously.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. FIG. 1 shows a focused ion beam (hereinafter, FI) having a sputter etching function using Ar as an ion species.
It is the figure which showed the processing apparatus 1 for b). The FIB processing apparatus 1 includes a sample stage 2 for fixing a cross-section observing sample 8 provided in a processing chamber, and a gas ejection nozzle for similarly ejecting a raw material gas W (CO) ₆ in the processing chamber in the direction of the sample stage. 3 and Ga, which is also provided in the processing chamber and irradiates the sample stage with a Ga ⁺ ion beam 4
The ion gun 5 is an ion gun 5, an ion gun 6 is also provided in the processing apparatus and uses Ar as an ion species for sputter etching in the sample stage direction, and a vacuum pump 7 for vacuuming the processing chamber.

FIG. 2 shows an example of a sample for observing a cross section. A semiconductor device pattern 10 is formed on a silicon (hereinafter abbreviated as Si) substrate 9 which is a sample, and the semiconductor device pattern 10 is formed. The cross-section observation point 11 is marked.

As shown in FIG. 3, the cross-section observation point 11 is centered on the cross-section observation point 11 by cutting and mechanical polishing.
It is processed into a size of 0.5 × 2.5 mm. The cross-section observation sample 8 thus processed is fixed on the sample stage 2 of the FIB processing apparatus 1. Then, as shown in FIG. 4, the source gas W (CO) ₆ ejected from the gas ejection nozzle 3 is irradiated onto the surface of the cross-section observation portion 11 and the peripheral portion from the ion gun 5 using Ga as the ion species Ga ^+. By decomposing and depositing with the ion beam 4, W
The film is evaporated to form a W evaporated film 12. Furthermore, FIG.
As shown in, in the ion gun 6 using Ar as an ion species,
The semiconductor device pattern 10 is removed by sputter etching the surface of the cross-section observation sample 8 at an angle of 45 degrees in the normal direction, and the W vapor deposition film 12 and the semiconductor device pattern 10 under the W vapor deposition film 12 remain. Rough processing is performed.

Such processing is possible because the semiconductor device pattern 10 is sputter-etched at a higher speed than the W deposited film 12. Thus, the W vapor deposition film 12 provided as a mask on the cross-section observation portion 11
And the difference in the sputter etching speed of the semiconductor device pattern 10
The semiconductor device pattern 10 at the cross-section observation portion 11 below and the peripheral portion can be selectively left. Also, W
If the material on the sample surface is sputter-etched at a slower rate or at the same rate as the deposition film 12 is sputter-etched, it is necessary to deposit the W film several times.

In the above description, the incident angle of the sputter etching by the ion gun 6 using Ar as the ion species is 45 degrees with respect to the normal line direction of the sample 8 for observing the cross section. The angle can be changed according to need considering the processing speed.

Further, as shown in FIG. 6, the W vapor-deposited film 12 in the extreme peripheral portion 13 of the cross-section observation sample 8 of FIG. 5 and the semiconductor device pattern 10 thereunder are irradiated from the ion gun 5 using Ga as an ion species. The Ga ⁺ ion beam 4 is used to perform sputter etching to thin the sample film to a thickness of 0.3 μm or less at which TEM observation is possible. As described above, the reason why the sample film thickness can be reduced to 0.3 μm or less at which TEM observation is possible is that Ga ⁺ ions that can focus the ion beam to several 100 nm are used.

A sample prepared for this TEM observation is shown in FIG.
As shown in FIG. 5, the cross section is arranged so that the cross section can be observed by the TEM, and the cross section of the cross section observation portion 11 is observed by causing a transmission electron beam 14 to be emitted from the electron gun (not shown) of the TEM and transmitted.

Thus, the semiconductor device pattern 10
Since the W deposition film 12 having a slower sputter etching rate than the semiconductor device pattern 10 is formed on the upper cross-section observation portion 11 and its peripheral portion, even if sputter etching is performed with an ion gun using Ar as an ion species, The cross-section observation portion 11 under the vapor deposition film 12 and the semiconductor device pattern 10 in the peripheral portion can be selectively left.

Further, as the main unit of the FIB processing apparatus 1,
In addition to the formation of the W deposition film 12 and the W deposition film 12 in the extreme peripheral portion 13 of the cross-section observation point 11 and the semiconductor device pattern 10 thereunder by sputter etching, in addition to the ion gun 5 using Ga as an ion species, high speed and Since the ion gun 6 using Ar as an ion species for performing sputter etching over a wide range is provided in the same apparatus for processing, there is no risk of destroying the cross-section observation point 11, and the cross-section observation sample 8 can be simply and quickly performed. Can be produced.

In the above embodiment, S is used as the semiconductor material.
Although the substrate using i is processed, a substrate using another semiconductor material can be processed by the same method.

[0022]

According to the method for preparing a sample for cross-section observation of the present invention, a W vapor deposition film having a slower sputter etching rate than the semiconductor device pattern is formed on the surface of the sample for cross-section observation in the peripheral portion including the cross-section observation portion. By performing sputter etching using Ar as an ion species on the surface of the sample for cross-section observation including the vapor-deposited film, the semiconductor device pattern other than the peripheral portion including the cross-section observation portion can be removed at high speed and in a wide range.

Further, the processing apparatus of the present invention can perform sputter etching in a wide range at high speed in addition to an ion gun using Ga as an ion species capable of forming a W vapor deposition film and sputter etching a minute area in the FIB processing apparatus. By providing an ion gun using Ar as an ion species, a cross-section observation sample can be prepared easily and in a short time without damaging the cross-section observation location.

[Brief description of drawings]

FIG. 1 is a front view of a sample preparation method for a transmission electron microscope and a focused ion beam processing apparatus according to an embodiment of the present invention.

FIG. 2 is a perspective view of a cross-section observation sample according to an example of the present invention.

FIG. 3 is a perspective view showing a first step of a method for manufacturing a cross-section observation sample in the example.

FIG. 4 is a perspective view showing a second step of the method for manufacturing the cross-section observation sample in the example.

FIG. 5 is a perspective view showing a third step of the method for manufacturing the cross-section observation sample in the example.

FIG. 6 is a perspective view showing a fourth step of the method of manufacturing the cross-section observation sample in the example.

FIG. 7 is a sectional view taken along line AA of FIG. 6 of the same embodiment.

FIG. 8 is a perspective view of a cross-section observation sample of a conventional example.

FIG. 9 is a perspective view showing a first step of a method for manufacturing a cross-section observation sample of the conventional example.

FIG. 10 is a second method of manufacturing a sample for observing a cross section of the conventional example.
The perspective view which shows a process.

FIG. 11 is a third example of a method for manufacturing a cross-section observation sample of the conventional example.
The perspective view which shows a process.

FIG. 12 is a sectional view taken along line BB of FIG. 11 of the conventional example.

[Explanation of symbols]

 1 Focused ion heme processing device 5 Ion gun using Ga as an ion species 6 Ion gun using Ar as an ion species 8 Cross-section observation sample 10 Semiconductor device pattern 11 Cross-section observation location 12 W evaporated film 13 Very peripheral area

Claims (6)

[Claims] 1. A material having a slow sputter etching rate is deposited on a sample surface at a cross-section observation site and its periphery to be observed by a transmission electron microscope, and the deposited sample surface containing the substance having a slow sputter etching rate is used as a material. Sputter etching is performed by using ions with a high sputter etching selection ratio, and only the cross-section observation point under the deposited substance with a slow sputtering rate and its peripheral portion are selectively left. Sample preparation method. 2. The substance having a low sputter etching rate is a metal film formed by a focused ion beam processing apparatus, and the ion having a large sputter etching selection ratio between materials is Ar. Transmission electron microscope sample preparation method. 3. The method for preparing a sample for a transmission electron microscope according to claim 2, wherein the metal film is a W vapor deposition film. 4. The method according to claim 1, wherein the sputter etching is performed with respect to the sample surface at a specific direction and angle.
Alternatively, the sample preparation method of the transmission electron microscope according to the item 2. 5. A material having a slow sputter etching rate is deposited on the sample surface at a cross-section observation point and its periphery observed by a transmission electron microscope, and the material is applied to the sample surface containing the deposited substance having a slow sputter etching rate. It is an apparatus for performing sputter etching using ions having a high inter-sputter etching selection ratio. For performing two types of sputter etching, an ion gun using Ga as an ion species and an ion gun using an ion species other than Ga as an ion species are provided. Characteristic focused ion beam processing equipment. 6. The two types of sputter etching guns are G
The focused ion beam processing apparatus according to claim 5, comprising an ion gun using a as an ion species and an ion gun using Ar as an ion species.