JPS5914243A - Scan-type ion microanalyzer - Google Patents

Abstract

PURPOSE:To eliminate insufficient sensitivity during microregion analysis by specifying the shape and number of analysis regions by luminescent lines in the analyzed region on the secondary ion image obtained by scanning the primary ions and opening the gate of a detector to extract the analyzed signal during the specified region scanning. CONSTITUTION:An adder 12 adds a secondary ion signal and a discrimination signal to generate an intensity modulation signal of a CRT13, which is in synchronism with the primary ion scanning, thereby displays an overlapped image of the secodary ion image on a sample surface and the luminescent lines of analysis regions set in a set circuit 17. On the other hand, the output from an discrimination circuit 16 becomes the switching signal of an extracting gate 8 of an analysis signal, thus opening the gate only while the primary ion beam 1 is scanning the analysis regions set by the set circuit 17 and displayed by the luminous lines on the CRT13. According to this constitution, the analysis regions can be determined in response to the shape of the analyzed object and the analysis regions of multiple points during one scan can be specified.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a scanning ion microanalyzer, and more particularly to an ion microanalyzer that is suitable for high-sensitivity analysis by arbitrarily changing the analysis area using a scanning secondary ion image.

Grain boundary -? When analyzing impurities in minute parts such as IC patterns, conventional methods include irradiation analysis with a stationary -order ion beam focused to the same extent as the target object, and methods that scan the center with a -order ion beam. Learn how to open the detector gate only when there is a problem. In the former, the accuracy of the surf distribution in the depth direction is poor because the current density of -order ions cannot be made uniform, and in both the former and the latter, there are drawbacks such as limitations in detection sensitivity in microscopic analysis. have.

SUMMARY OF THE INVENTION An object of the present invention is to provide a highly sensitive ion microanalyzer that eliminates the lack of sensitivity in microarea analysis and is more suitable for microanalysis.

The present invention specifies the shape and number of analysis regions on a secondary ion image obtained by scanning -order ions using bright lines, and opens the gate of the detector during scanning of the finger and foot in the habitual region. By capturing analysis signals, the lack of sensitivity in minute area analysis can be eliminated, making it suitable for more detailed analysis.

Examples of the present invention will be described below.

#! FIG. 1 shows an embodiment of the invention.

In the figure, the -order ion beam 1 is deflected by the polar power source 1.
The sample 3 is deflected and scanned by the deflection electrode 2 connected to the sample 3. A part of the secondary ions 4 emitted from the sample 3 cannot be detected by the detector 10 and is amplified by the amplifier 11 . Secondary ion 4
0 Most of the Jxt is separated by IXf analyzer 5 and sent to detector 6.
The signal is detected as an analysis signal, amplified by the amplifier 7, and stored in the storage device i19 via the gate 8. - A scanning signal for the deflection electrode power source for the next ion is generated by the function generator 18.

This scanning signal is supplied to the deflection coil power supply 15 and discrimination circuit 16 of the CRT 13. The discrimination circuit 16 outputs a discrimination signal to the adder 12 and the gate 8 when the scanning signal reaches the value set by the setting circuit 17. The adder 12 adds the secondary ion signal and the discrimination signal to produce a brightness modulation signal of C1tT13.

Since the CRT 13 is synchronized with the -order ion scanning, it displays a superimposed image of the secondary ion image on the sample surface and the bright line of the analysis area set by the setting circuit 17.

On the other hand, the output of the discrimination circuit 16 is
It becomes the opening/closing signal of C1tT13 and is set by the setting circuit 17.
The gate is opened while the ion beam 1 is partially scanning the analysis region indicated by the bright line.

FIG. 2 shows the secondary ion image of the CRT and the pattern of bright #+1 display. The part with the oblique edge in the figure is the subject of microanalysis, and the travel xmrq area is Xo −) (maX, Yo −
Let YmaX be X+ , Xt , Xs , X4
and Yl+Y, , Y, , Y4 are bright lines.

In Figure 3, A is the X scanning signal and discrimination circuit output signal at points Y1 and Y3, H and D are the bright gland signals, and C and E.
represents the gate signal.

According to the above configuration, since the analysis area can be determined according to the shape of the object to be analyzed, and the analysis area can be specified for several nuclei during scanning, the accumulation storage time can be increased during one scan. The sensitivity can be improved. Since it is possible to scan a relatively wide range, it has the advantage of being able to perform sputtering uniformly, and improving analysis accuracy because there is no mixing of unnecessary signals around the scanning range.

FIG. 4 shows another embodiment of the present invention. The output of the amplifier 11 is used as a brightness modulation signal for the CRT 13 and is input to the discrimination circuit 16. The determination circuit 16 compares and determines the setting value B of the setting circuit 17 and the output A of the amplifier 11.
)B, the voltage shown in FIG. 5C is output. The output C of the discrimination circuit 16 becomes an opening/closing signal for the detection section gate 8.

By using the above method, it is possible to automatically select and analyze by using the difference in contrast of specific elements. In this case, manual setting using the n-line shown in FIG. 2 is not necessary.

In the embodiments, the secondary ion image detector and the analytical detector are independently provided, but it is possible for one analytical detector to also serve as an image display. In addition, when the number of analysis areas specified is 2, it is 6 or more, which is a favorable translation. Therefore, according to this embodiment: (1) Detection sensitivity is improved by the increase in the analysis area.

(2) Since there is no contamination of signals from areas other than the analysis target, detection sensitivity is improved and analysis accuracy is increased.

(3) Since the ion beam partially scans a relatively wide area, the uniformity of sputtering is good, and the degree of depth analysis is increased.

There are effects such as Note that this embodiment uses a high-intensity ion gun as a -order ion source, and is an extremely effective analysis method for analyzing minute parts of 1 μm or less. Currently, some ion beam diameters are 1 μn]φ, and the analysis area is 5~
This is effective when the thickness is 10 μm or more.

As described above, according to the present invention, the lack of sensitivity in micro area analysis can be eliminated.

[Brief Description of the Drawings] Fig. 1 is a diagram showing an embodiment of the present invention, Fig. 2 is a diagram showing a pattern of a secondary ion image and bright line display of a CRT, and Fig. 3 is a main time chart of Fig. 1. , FIG. 4 is a diagram showing another embodiment of the present invention, and FIG. 5 is a main time chart of FIG. 4. 8...Gate, 12...Adder, 13...CRI
', 14... Deflection electrode power supply, 15... CRT deflection coil power supply, 16... Discrimination circuit, 17... Setting circuit,
18...Function generator. Spear 4M! ”L-

Claims (1)

[Claims] 1. Scan the sample surface with a primary irradiation particle beam, and among the secondary emission particles generated by the beam irradiation, secondary emission particles generated within a pre-specified area within the primary irradiation particle scanning range of the sample. In a scanning ion microanalyzer that selectively outputs only information from A scanning ion microanalyzer characterized in that a second means for in-analyzing and detecting and storing secondary ions is provided, and a gate of the twentieth means is opened and closed in response to the discrimination signal.