JPH0555333A - Foreign matter analyzer - Google Patents

Abstract

PURPOSE:To precisely perform the overall component analyzing step of any foreign matters existing on the surface of an element to be inspected such as a wafer, etc., regardless of the fineness of the foreign matters by a method wherein the output signals of reflected analyzing beams are integrated by an integrating means to perform the overall component analyzing step in terms of the output. CONSTITUTION:An analyzing circuit 5 processes the output signals from a detector 4 to output signals A analyzing respective components in one analysis area. Next, an integrating circuit 6 integrates the signals A successively outputted from the analyzing circuit 5 to output the other signals B. Next, the subtracting circuit 8 subtracts the output signals of a dustless integrated value output circuit 7 from the output signals B of the integrating circuit 6 to output the signals C analyzing the foreign matter components only. At this time, the purpose of the subtraction of the output signals of the dustless integrated value output circuit 7 from the output signals B of the integrating circuit 6 is to obtain the components of the foreign matters only. Through these procedures, the whole foreign matters existing in respective analysis areas are provided to furnish the component analysis results of the foreign matters as the object of component analysis regardless of the fineness thereof.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a foreign substance analyzer, and more particularly to a foreign substance analyzer capable of analyzing foreign substances adhering to the surface of a semiconductor wafer or the like without ignoring minute foreign substances.

[0002]

2. Description of the Related Art One of the most important items in the manufacture of semiconductor devices is to prevent foreign matter from adhering to the surface of a semiconductor wafer. For that purpose, it is effective to cut off the foreign matter generation source. is there. In order to cut off the foreign matter generation source, it is essential to accurately analyze the components of the entire foreign matter on the wafer in each process.

By the way, conventionally, in the component analysis of foreign matter, as shown in FIG. 4, a laser type foreign matter address inspection apparatus using a laser is used to detect an address where each foreign matter exists on a wafer, and then the foreign matter address is detected. Based on the foreign particle address data obtained by the inspection apparatus, the foreign particle analysis apparatus irradiates an address where foreign particles exist on the wafer with X-rays as an analysis beam, and the reflected beam is detected by a detector.
It was performed by the method of judging the component of the foreign matter from the spectrum of the output waveform of the detector. FIG. 5 is a plan view showing an example of foreign matter address output from the foreign matter address inspection apparatus.

[0004]

By the way, in the past, the component analysis was carried out for each individual foreign substance, but according to the conventional method, it is possible to analyze a large foreign substance having a diameter of 1 μm or more, but less than that. It is difficult to analyze the component of the fine foreign matter, and the component analysis of the foreign matter of 0.3 μm or less is impossible. This is because the laser-type foreign matter address inspection device has a limit in address detection accuracy, and the foreign substance analyzer also has a limited drive precision in a drive mechanism for accessing a foreign substance on a wafer according to address data. That is,
It is difficult for a foreign substance analysis device to match a fine foreign substance to the analysis area. Therefore, it is difficult to analyze fine foreign matters.

By the way, large dust particles have been reduced due to the improvement of dust-proof measures, but on the other hand, finer dust particles cannot be ignored because of the higher integration of integrated circuits and the miniaturization of semiconductor elements. Therefore, it is becoming impossible to perform accurate foreign substance component analysis if the fine foreign substances are not included in the target of the component analysis for cutting off the foreign substance generation source.
Furthermore, it becomes difficult to take appropriate measures against foreign substances.

FIG. 6 is a particle size distribution diagram of foreign matter in various steps showing this, and most of the foreign matter generated as shown in Case A has a diameter of 1.0 μm or more. In some cases, most of the foreign matter generated as shown in Case B is a minute foreign matter having a diameter of 0.3 to 0.5 μm. The component of the foreign matter does not always change depending on the size, but it often changes depending on the size. Therefore, it is impossible to accurately grasp the component of the pollution source if only the large foreign matter is subjected to the component analysis.

Therefore, an attempt has been made to detect a minute foreign substance by reducing the diameter of the analysis beam to narrow the analysis area. However, by narrowing the analysis area, each minute foreign substance can be detected. There is also a problem in conducting component analysis. This is because when the analysis beam is narrowed down to narrow the analysis area and there is a particle larger than the beam diameter as shown in FIG. 7, the beam spot of the analysis beam is completely positioned on the particle. Without doing so, it may partly come off the foreign object. In this case, the component analysis result obtained by the detection is greatly affected by the surface of the silicon semiconductor wafer, which is not preferable.

The present invention has been made to solve the above problems, and accurately analyzes the entire components of foreign substances existing on the surface of an object to be inspected such as a wafer regardless of whether they are fine or not. The purpose is to be able to do.

[0009]

The foreign matter analyzer according to the present invention comprises:
An output signal for each analysis area of a detector for detecting a reflected beam of an analysis beam in one analysis area is integrated by an integration means, and the overall component analysis of foreign matter is performed from the output of the integration means. It is characterized by

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The foreign matter analyzer of the present invention will be described in detail below with reference to the illustrated embodiments. FIG. 1 is a block diagram showing an embodiment of the foreign matter analyzer of the present invention, FIGS. 2 (A) to 2 (C) show examples of moving different analysis areas, and FIGS. 3 (A) to 3 (C).
FIG. 3 is a waveform diagram of various signals A, B and C in FIG. In the drawings, 1 is an XY stage, 2 is a semiconductor wafer to be inspected,
3 is a light source for irradiating the wafer 2 with X-rays as an analysis beam, 4 is a detector for detecting a reflected beam of the analysis beam reflected on the surface of the semiconductor wafer 2, and 5 is an output signal of the detector 4. An analysis circuit for processing the signal outputs a signal A obtained by analyzing each component in one analysis area.

Reference numeral 6 is an integrating circuit for integrating the signals A for each analysis area, which are sequentially output from the analysis circuit 5, and the output signal is B. Reference numeral 7 denotes a dustless integral value output circuit, which outputs the integral value of the peak value of the waveform of the portion where the foreign matter (dust) of silicon does not exist, in other words, the portion where the component is composed only of silicon.

Reference numeral 8 is a subtraction circuit for subtracting the output signal of the dustless integrated value output circuit 7 from the output signal B of the integration circuit, and outputs a signal C for component analysis of only the foreign matter. In this way, from the output signal B of the integrating circuit 6 to the dustless integrated value output circuit 7
Is subtracted by the subtraction circuit 8 because the output signal B of the integration circuit 6 also includes a signal indicating the component of the silicon itself of the wafer, and subtracting this signal yields only the component of the foreign matter. This is because It should be noted that the dustless integrated value output circuit 7 may output a value obtained by accumulating a signal indicating a silicon component in each analysis area each time the analysis area is moved, or may indicate a silicon component for all analysis areas. Various embodiments are conceivable, such as having an integrated value of signals from the beginning, and this output may be subtracted from the output of the integrating circuit 6 at the final stage to obtain the analysis result.

The present foreign matter analyzer does not acquire foreign matter address data by the foreign matter address inspection apparatus and access the foreign matter address based on the data to analyze the components of the foreign matter, and move the analysis area on the wafer. Then, the component analysis result for each analysis area is integrated for the entire surface of the wafer, the entire effective region, or a specific region of the effective region to perform component analysis for the entire foreign matter.

Then, the diameter of the analysis beam is set to, for example, 1.
The analysis area is made relatively large, such as 0, 1.5, or 0.5 μm, and individual foreign substances are not analyzed one by one. After the analysis, the analysis area is moved, the component analysis for each analysis area is integrated, and the component analysis is performed for the entire foreign matter on the wafer or for the entire foreign matter in the specific area to provide a material for cutting off the foreign matter generation source.

FIG. 2 (A) shows a case where the circular analysis areas (diameter 1.0 μm) are moved without overlapping and at intervals, and the analysis is carried out. There are some unanalyzed parts. Figure 2
A circular analysis area (diameter 1.5 μm) is shown in (B).
It is a case where the components are analyzed by moving them so that there is no part where the components are not analyzed.
The most accurate component analysis result is obtained. On the other hand, Fig. 2
Shown in (C) is a case where the analysis area (diameter 0.5 μm) is moved at intervals, and in this case, the portion where the component analysis is not performed becomes very wide, and the accuracy of the component analysis result becomes slightly lower.

According to the foreign matter analyzing apparatus of the present invention, the foreign matter existing in each analysis area is subjected to the component analysis regardless of whether it is fine or not, and the result of the component analysis of the foreign matter is prepared. Therefore, unlike the conventional case, there is no fear that minute foreign matter is ignored, and it becomes possible to accurately perform the overall component analysis of the foreign matter on the wafer. Therefore, more accurate data for cutting off the foreign matter generation source can be obtained, which can effectively contribute to cutting off the foreign matter generation source.

[0017]

The foreign matter analyzer of the present invention integrates the outputs of the detector which detects the reflected beam of the analysis beam from the analysis area irradiated with the analysis beam and the detector which changes for each analysis area. And at least an integrating means for
It is characterized in that the component of the foreign matter is analyzed from the output of the integrating means. Therefore, according to the foreign matter analyzing apparatus, all the foreign matter existing in each analysis area is subjected to the component analysis regardless of whether it is fine or not, and is used for the component analysis of the foreign matter. Therefore, unlike the conventional case, there is no fear that minute foreign matter is ignored, and it becomes possible to accurately perform the overall component analysis of the foreign matter on the wafer.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing one embodiment of a foreign matter analyzer of the present invention.

FIG. 2A to FIG. 2C are diagrams showing examples of moving different analysis areas.

FIG. 3A to FIG. 3C are waveform diagrams of various signals.

FIG. 4 is an explanatory diagram of a conventional example.

FIG. 5 is a plan view showing an example of foreign matter address output in a conventional example.

FIG. 6 is a foreign particle size distribution chart showing particle size distributions of foreign materials in various processes.

FIG. 7 is a diagram showing a case where the beam diameter for analysis, which is one problem in the conventional art, is reduced.

[Explanation of symbols]

 2 wafer 4 detector 6 integrating means 7 dustless integrated value output circuit 8 subtracting circuit A, B, C signals

Claims (1)

[Claims] 1. A detector for detecting a reflected beam of an analysis beam from an analysis area irradiated with the analysis beam, and an integrating means for integrating an output of the detector for each analysis area, at least: A foreign matter analyzing apparatus characterized in that the component of the foreign matter is analyzed from the output of the integrating means.