JP2001044253A - Inspection of semiconductor device and inspection apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect with high sensitivity foreign matters adhering to the microscopic patterns formed on the surface of a semiconductor device and the location of the defect, such as an abnormality in the patterns. SOLUTION: In a semiconductor device S with a plurality of line patterns A, B, C, etc., formed on its surface, a beam from an electron gun 8 is radiated on one pattern, such as the pattern A, among the line patterns A, B, C, etc., and characteristic X-rays from the pattern A are detected by a detector 9 to obtain data (a) for the analysis of an element being contained in the pattern A. Data (b) for the analysis of an element being contained in the pattern B and data (c) for the analysis of an element contained in the pattern C are obtained by the same method as the method capable of obtaining the data (a). By comparing the data (a) and the data (b) with each other, and the data (b) and the data (c) with each other, this difference among the forms of the patterns A, B and C are decided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for inspecting a semiconductor device, and more particularly to a method and an apparatus for inspecting a semiconductor device used for inspecting minute pattern defects.

[0002]

2. Description of the Related Art In recent years, with the miniaturization of semiconductor devices, it has become important to grasp the processed shape (pattern) of the device.

Conventionally, in order to confirm whether or not the shape of a large number of minute patterns existing in a sample is uniform,
A so-called laser scattered light detection type method of irradiating a sample with a laser, detecting the scattered light, and setting an arbitrary threshold has been used.

As another conventional technique, there is a so-called image comparison type method in which a sample is irradiated with light to obtain an image of a pattern of an element to be inspected, and then two or more detection outputs are compared and determined. there were.

[0005]

In the above-mentioned conventional method for detecting an abnormal portion of a pattern, since the detection sensitivity greatly depends on the pattern shape of the semiconductor device, it is difficult to adjust the detection sensitivity, and an important defect is overlooked. Many things have happened.

For example, in the above-described laser scattered light detection type method, the detection sensitivity is low for a flat and not very high foreign material such as a resist residue and an etching residue because the obtained laser scattered light is weak. In addition, when the sample is irradiated with a laser, there is also laser scattered light from a normal pattern, so there is a difficulty in eliminating them and efficiently extracting only the laser scattered light from foreign matter and abnormal patterns. Therefore, the detection efficiency of foreign substances and abnormal patterns was extremely low.

[0007] Also, in the image comparison type method, for example, the polysilicon residue after polysilicon dry etching can be used.
The detection sensitivity was extremely low for needle-like foreign substances having a height but a small diameter. Furthermore, even when the shape looks the same, such as a partial abnormality when polysilicon is converted to tungsten silicide (so-called poor silicidation), it has not been possible to detect an abnormal pattern with a different material at all.

[0008] This is because the image comparison type method utilizes a difference in contrast of an image obtained by a CCD camera or the like. Therefore, for a material such as polysilicon, the reflectance and the grain (particle) are high. This is because the size greatly affects the contrast of the image.

On the other hand, when a foreign substance is present on a fine pattern formed on the surface of a semiconductor device, a method for knowing the constituent elements of the foreign substance is as follows. There is a method of detecting the obtained characteristic X-rays and performing an ex post analysis using a pulse height analyzer or the like.

However, this method cannot be used unless a foreign substance to be subjected to composition analysis is specified beforehand. Therefore, this method cannot be used unless an abnormal part of a pattern can be detected. there were. Therefore, the method of analyzing compositional elements by electron beam irradiation has not been used for the purpose of detecting foreign matter, pattern abnormality, and the like.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a semiconductor device inspection method and an inspection device capable of detecting a defect portion such as a foreign substance attached to a fine pattern of a semiconductor device or an abnormality of the pattern with high sensitivity.

[0012]

SUMMARY OF THE INVENTION A method of inspecting a semiconductor device according to the present invention is directed to a semiconductor device having a plurality of fine patterns formed on a substrate. An inspection method of an apparatus, wherein a characteristic X-ray is generated by sequentially irradiating each pattern of a plurality of patterns with an electron beam or X-rays, and the constituent elements of each pattern are analyzed from the sequentially generated characteristic X-rays. It is characterized in that an abnormality of the pattern and the presence / absence of a foreign substance are determined by comparing the analyzed data for each analyzed pattern.

According to this inspection method, an X-ray is generated by irradiating the pattern with an electron beam, the compositional elements of the pattern are analyzed from the generated X-ray, and the analysis data for each pattern is compared. The difference between the patterns becomes clear, and it is possible to detect a defective portion such as a foreign substance attached to the minute pattern or an abnormality of the pattern with high sensitivity.

A semiconductor device inspection apparatus according to the present invention is an apparatus for inspecting a semiconductor device in which a plurality of minute patterns are formed on a substrate, for abnormality of the pattern and presence / absence of foreign matter adhering to the pattern. A stage on which a semiconductor device is installed, a driving unit capable of controlling the position coordinates of the stage, an electron gun for generating an electron beam, and a characteristic X generated by irradiating the pattern with the electron beam.
X-ray detection means for detecting X-rays, analysis means for analyzing compositional elements of the pattern from characteristic X-rays detected by the X-ray detection means, and abnormalities in the pattern by comparing a plurality of analysis data analyzed by the analysis means. A determining means for determining the presence or absence of a foreign substance is provided.

An X-ray tube for generating X-rays is provided in place of the electron gun, and the X-ray detecting means detects characteristic X-rays generated by irradiating the pattern with X-rays generated by the X-ray tube. You may make it.

With this inspection apparatus, the inspection method for a semiconductor device according to the present invention can be carried out, and a defective portion such as a foreign substance adhering to a fine pattern of a semiconductor device or an abnormal pattern can be detected with high sensitivity.

Further, since the operating mechanism of the drive unit for controlling the position coordinates of the stage is constituted by a piezo element for raising and lowering the stage, the stage can be minutely moved, thereby being installed on the stage. The pattern of the semiconductor device can be accurately adjusted to the irradiation position of the electron beam.

[0018]

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

(First Embodiment) FIG. 1 shows a first embodiment of the present invention.
FIG. 3 is a diagram showing a configuration of a semiconductor device to be inspected and an inspection device according to the embodiment.

The semiconductor device S to be inspected has line patterns A, B, C,... Formed on an oxide film 2 formed on the surface of a semiconductor substrate 1. These line patterns A, B, C,... Are formed by, for example, patterning polysilicon deposited on the oxide film 2 by using a known lithography and etching technique, and then doping with phosphorus. It is formed by forming tungsten.

The semiconductor device inspection apparatus according to the first embodiment has a stage 5 on which the semiconductor device S is installed horizontally. The stage 5 can be moved in a horizontal direction and a vertical (elevation) direction by a motor (not shown) installed in the stage 5. Further, in order to move the stage 5 minutely in the vertical direction, a piezo element is used. 6
Is provided. That is, for example, 0.4 μm along each line pattern A, B, C,.
Even if the pitch is about m, the semiconductor device S can be accurately moved to irradiate the electron beam. Note that 7
Is a controller for controlling the operation of the stage 5 and the driving of the piezo element 6.

An electron gun 8 is provided above the stage 5 so that each of the line patterns A, B, C,... Of the semiconductor device S is irradiated with an electron beam vertically. A characteristic X-ray detector 9 is installed so that characteristic X-rays from a line pattern irradiated with an electron beam by the electron gun 8 can be detected, and elements can be analyzed from the characteristic X-rays detected by the characteristic X-ray detector 9. A wave height analyzer 10 is provided so as to be able to. A computer 11 for recording data of the analysis is connected to the pulse height analyzer 10.

The computer 11 has a memory (not shown) for storing a plurality of analysis data from the pulse height analyzer 10 and has a program for comparing the analysis data to determine whether there is an abnormality.

In the inspection apparatus shown in FIG. 1, the piezo element 6 and the controller 7 are driving units for controlling the position coordinates of the stage 5, the characteristic X-ray detector 9 is X-ray detecting means, and the wave height analyzer Reference numeral 10 denotes analysis means, and the computer 11 includes determination means.

FIG. 2 is a flowchart showing a method for inspecting each line pattern A, B, C,... Of the semiconductor device S using the inspection apparatus shown in FIG. FIG. 3A is a side view of the semiconductor device S, and FIG. 3B is a plan view of the semiconductor device S. For line pattern A, the line width is 0.25 μm, the line height is 0.3 μm, and the material is
It is assumed that tungsten silicide 4A is formed on polysilicon 3A. As for the line pattern B, the line width is 0.25 μm, the line height is 0.3 μm,
The material is polysilicon 3 as in the case of the line pattern A.
It is assumed that tungsten silicide 4B is formed on B. For the line pattern C, the line width is 0.25 μm, the line height is 0.3 μm, and the material is
Unlike the line patterns A and B, it is assumed that it is made of only polysilicon 3C and no tungsten silicide is formed. FIG. 4 shows the analysis data of each of the line patterns A, B, and C that have been subjected to elemental analysis by the pulse height analyzer 10. Hereinafter, the line patterns A, B, C,... Will be described as the first, second, and third line patterns with reference to the flowchart of FIG.

When inspecting the semiconductor device S having the line patterns A, B, C,..., The semiconductor device S is placed horizontally on the stage 5 (step S1 in FIG. 2). In FIG. 2, the total number of line patterns A, B, C,.
(Step S2), and from SA to SB until n> N
Are repeated. In step S3, n is changed to n +
By setting it to 1, n is set to 1.

Next, an electron beam is irradiated from the electron gun 8 onto the first line pattern, for example, A, which is one of the line patterns A, B, C,... (Step S4).

The characteristic X-ray from the line pattern A is detected by the detector 9, and the characteristic X-ray is detected by the peak height analyzer 10.
Elemental analysis is performed using the line (step S5). The data obtained by this analysis is referred to as analysis data
(Step S6). The analysis data a is, for example,
It is assumed that FIG.

Next, in step S7 of FIG. 2, n and 2 are compared. In this case, since n is 1 and 2 or less, the flow returns to step S3, and n is set to 2.

Next, the stage 5 is moved by controlling the piezo element 6 so that the second line pattern B is irradiated with the electron beam, and the line pattern B is irradiated with the electron beam (step S4).

In this case as well, characteristic X-rays from the line pattern B are detected by the detector 9, and the pulse height analyzer 10 performs elemental analysis using the characteristic X-rays (step S5).
The analyzed data is stored in the computer 11 as analysis data b (step S6). It is assumed that the analysis data b is, for example, FIG.

Next, in step S7 of FIG. 2, since n is 2 or less, the process returns to step S3, where n is set to 3.

Next, the stage 5 is moved by controlling the piezo element 6 so that the third line pattern C is irradiated with the electron beam, and the line pattern C is irradiated with the electron beam (step S4).

In this case as well, characteristic X-rays from the line pattern C are detected by the detector 9, and the pulse height analyzer 10 performs elemental analysis using the characteristic X-rays (step S5).
The analyzed data is stored in the computer 11 as analysis data c (step S6). It is assumed that the analysis data c is, for example, FIG.

Next, in step S7 of FIG.
Since n is larger than 2, the process proceeds to step S8.

Next, the analysis data a and b are compared by the computer 11 (step S8). That is, FIG.
(A) and (B) are compared. As a result, it can be determined that there is no large difference between the two pieces of analysis data a and b and they are equal. In other words, it can be determined that both line patterns A and B are formed as substantially the same pattern.

Next, the analysis data b and c are compared by the computer 11 (step S9). That is, FIG.
(B) and (C) are compared. As a result, the analysis data b has W, P, Si, and O, whereas the analysis data c has P, Si, and O but no W, so that there is a large difference between the analysis data b and c. Because there is, it can be determined that they are not equal.
In other words, the two line patterns B and C have different materials, and can be clearly judged to be different patterns.

As described above, in step S8, it is determined that the analysis data a and b are equal, and then in step S9 it is determined that the analysis data b and c are not equal (different). It is determined that it is abnormal (step S11). That is, as described above, by irradiating the electron beam, detecting the characteristic X-ray from the pattern, and comparing the analysis data from the pattern, the line pattern C among the line patterns A, B, and C becomes different from the others. It can be seen that the formation is abnormal. Not shown,
The process returns to step S3 in FIG. 2 for the fourth and subsequent line patterns other than the line patterns A, B, and C, and the same processing is performed.

The analysis data a, b, and c are indicated by the types of the elements constituting the line patterns A, B, and C and the detected amounts of the elements. If at least one of the two is different, it is determined that the patterns are different, that is, one of them is abnormal, and if both the element type and the element detection amount of the two analysis data are the same, the patterns are determined to be the same. it can.

For example, when the film thicknesses of the tungsten silicides 4A and 4B of the line patterns A and B are different,
How much difference in film thickness can be detected depends on the detection accuracy of the characteristic X-ray detector 9.

In this embodiment, the analysis data of the elements are compared and the difference is detected.
The detection function (detection algorithm) can obtain analysis data and detect any foreign matter regardless of the shape of the foreign matter. Therefore, it is possible to detect a foreign matter having a pattern attached thereto, particularly a foreign matter which is flat and has a very small height, and a needle-like foreign matter having a height but a small diameter.

As described above, according to the present embodiment, the characteristic X-rays are generated by irradiating the line patterns A, B, C,.
From the characteristic X-rays generated, line patterns A, B, C,
The compositional elements of ... are analyzed, and each line pattern A, B, C,
By comparing the analysis data for..., Differences between the respective line patterns A, B, C,... Become clear, and defective portions such as foreign matters adhering to minute patterns and pattern abnormalities can be detected with high sensitivity. . Further, the sample (semiconductor device S) can be inspected nondestructively.

Moreover, even if the number of line patterns A, B, C,... Is large, the analysis and comparison of the analysis data can be performed in a short time by using a simple algorithm for examining the difference between the analysis data. , Efficient inspection is possible.

The number of line patterns A, B, C,..., The line width, the line height, and the material are not limited to those shown in the first embodiment. Not limited to the line, a contact hole or the like may be used.

In this embodiment, as is apparent from the flowchart of FIG. 2, three or more patterns are inspected. If the inspection is stopped during the inspection of three or more patterns, However, if three or more pieces of analysis data are obtained, it is possible to make a determination on those pieces of analysis data.

In the first embodiment, characteristic X-rays from a pattern are detected. Instead, fluorescent X-rays (characteristic X-rays generated by X-ray irradiation) are detected. Can also. In that case, instead of the electron gun 8, X
An X-ray tube for irradiating a ray is used. At that time, a fluorescent X-ray detector can be used instead of the characteristic X-ray detector 9.

(Second Embodiment) FIG. 5 shows a second embodiment of the present invention.
FIG. 2 is a diagram illustrating a configuration of a semiconductor device to be inspected and an inspection apparatus according to the first embodiment, and portions corresponding to the configuration of the first embodiment illustrated in FIG. 1 are denoted by the same reference numerals.

In the second embodiment, instead of the characteristic X-ray detector 9 and the pulse height analyzer 10 in the first embodiment, a curved spectrometer placed on a Rowland circle for Bragg reflection of characteristic X-rays is used. A crystal 12, a slit 13 for passing the reflected characteristic X-ray, and a proportional counter 14 for detecting the characteristic X-ray passed through the slit 13 are provided, and the output of the proportional counter 14 is connected to the computer 11. . The characteristic X-ray is divided into each wavelength by the curved spectral crystal 12. The slit 13 is made of, for example, Al or SUS, and characteristic X-rays generated from the semiconductor device S to be inspected are reflected by the curved spectral crystal 12, pass through the slit 13, and pass through the proportional counter 14.
It is set so that it can enter.

In the inspection apparatus shown in FIG. 5, the piezo element 6 and the controller 7 are driving units for controlling the position coordinates of the stage 5, the proportional counter 14 is an X-ray detecting means, and the computer 11 is an analyzing means. And determination means.

An inspection method of the semiconductor device S using the inspection device shown in FIG. 5 will be described. A flow chart showing the inspection method is shown in FIG. 2 similarly to the first embodiment,
This is a method for inspecting three or more patterns. The semiconductor device S is the same as that of the first embodiment. The line patterns A, B, and C have a line width of 0.25 μm and a line height of 0.3 μm, respectively. The material of B is tungsten silicide 4A, 4B formed on polysilicon 3A, 3B, and the material of line pattern C is different from line pattern A, B and consists only of polysilicon 3C, and tungsten silicide is formed. No.

When inspecting the semiconductor device S, the semiconductor device S is placed horizontally on the stage 5 (step S1). Thereafter, one of the line patterns A, B, C,.
An electron beam is emitted from the electron gun 8 to the second line pattern, for example, A (step S4).

Then, the characteristic X-rays from the line pattern A are Bragg-reflected by the curved spectral crystal 12, passed through the slit 13, detected by the proportional counter 14, and analyzed by the computer 11 (step S5). Is stored as analysis data a (step S6).

Next, the stage 5 is moved by controlling the piezo element 6 so that the line pattern B is irradiated with the electron beam, and the line pattern B is irradiated with the electron beam (step S4).

Also in this case, characteristic X-rays from the line pattern B are reflected by the curved spectral crystal 12 by Bragg reflection.
Through the slit 13, detection is performed by the proportional counter 14, and the detected data is analyzed by the computer 11 (Step S)
5) and store it as analysis data b (step S6).

Next, the stage 5 is moved by controlling the piezo element 6 so that the line pattern C is irradiated with the electron beam, and the line pattern C is irradiated with the electron beam (step S4).

Also in this case, characteristic X-rays from the line pattern C are reflected by the curved dispersive crystal 12 by Bragg reflection.
Through the slit 13, detection is performed by the proportional counter 14, and the detected data is analyzed by the computer 11 (Step S)
5) Store as analysis data c (step S6).

Here, the analysis data a,
b and c are, for example, exactly the same as the analysis data a, b and c in the first embodiment, and are shown in FIGS.
(C).

Next, the computer 11 first compares the analysis data a and b (step S8). That is, FIGS. 4A and 4B are compared. As a result, it can be determined that there is no large difference between the two pieces of analysis data a and b and they are equal. In other words, it can be determined that both line patterns A and B are formed as substantially the same pattern.

Next, the analysis data b and c are compared by the computer 11 (step S9). That is, FIG.
(B) and (C) are compared. As a result, the analysis data b has W, P, Si, and O, whereas the analysis data c has P, Si, and O but no W, so that there is a large difference between the analysis data b and c. Because there is, it can be determined that they are not equal.
In other words, the two line patterns B and C have different materials, and can be clearly judged to be different patterns.

As described above, in step S8, it is determined that the analysis data a and b are equal, and then in step S9 it is determined that the analysis data b and c are not equal (different). It is determined that it is abnormal (step S11). That is, as described above, by irradiating the electron beam, detecting the characteristic X-ray from the pattern, and comparing the analysis data from the pattern, the line pattern C among the line patterns A, B, and C becomes different from the others. It can be seen that the formation is abnormal. Not shown,
The process returns to step S3 in FIG. 2 for the fourth and subsequent line patterns other than the line patterns A, B, and C, and the same processing is performed.

According to the present embodiment, similarly to the first embodiment, the line patterns A,
By irradiating an electron beam to B, C,..., A characteristic X-ray is generated, and from the generated characteristic X-ray, the composition elements of the line patterns A, B, C,. By comparing the analysis data for C,..., The differences between the line patterns A, B, C,... Become apparent, and defective portions such as foreign substances adhering to minute patterns and abnormal patterns are detected with high sensitivity. Can be. Further, the sample (semiconductor device S) can be inspected nondestructively.

Moreover, even if the number of line patterns A, B, C,... Is large, the analysis and comparison of the analysis data can be performed in a short time by processing using a simple algorithm for examining the difference between the analysis data. , Efficient inspection is possible.

Further, in the second embodiment, since the characteristic X-ray is divided into each wavelength by the curved dispersive crystal 12, trace elements and light elements can be detected and analyzed, and element resolution is high and sensitivity is high. High inspection is possible.

The number of the line patterns A, B, C,..., The line width, the line height, and the material are not limited to those shown in the second embodiment. Not limited to the line, a contact hole or the like may be used.

In the second embodiment, as in the first embodiment, an X-ray tube is used in place of the electron gun 8 and fluorescent X-rays are used.
It can also be configured to detect lines.

[0066]

According to the present invention, X-rays are generated by irradiating a pattern formed on a semiconductor device with an electron beam, and the compositional elements of the patterns are analyzed from the generated X-rays. By comparing the data, the difference between the patterns becomes clear, and it is possible to detect a defective portion such as a foreign substance adhered to the minute pattern or an abnormality of the pattern with high sensitivity.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a semiconductor device to be inspected and a configuration of the inspection device according to a first embodiment of the present invention;

FIG. 2 is a flowchart showing a method of inspecting each line pattern of a semiconductor device using the device shown in FIG.

3 is a side view and a plan view of the semiconductor device of FIG.

FIG. 4 is a view showing line patterns A, B, and
The figure which shows the example of the analysis data of C.

FIG. 5 is a diagram showing a semiconductor device to be inspected and a configuration of the inspection device according to a second embodiment of the present invention.

[Explanation of symbols]

 S semiconductor device 1 semiconductor substrate 2 oxide film 3A, 3B, 3C polysilicon 4A, 4B tungsten 5 stage 6 piezo element 7 controller 8 electron gun 9 characteristic X-ray detector 10 wave height analyzer 11 computer

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2G001 AA01 AA03 BA04 BA05 CA01 EA01 GA06 GA08 HA01 HA13 KA01 KA03 LA11 MA05 NA07 NA15 NA17 PA11 PA14 4M106 AA01 BA02 BA20 CA39 CA41 CB21 DB01 DB21 DB30 DJ18 DJ20 DJ21 5C033 PP05 PP08

Claims (4)

[Claims] 1. A semiconductor device inspection method for inspecting a semiconductor device having a plurality of fine patterns formed on a substrate for abnormality of the pattern and presence / absence of a foreign substance attached to the pattern. Each pattern of the pattern is sequentially irradiated with an electron beam or X-ray to generate characteristic X-rays, the constituent elements of each pattern are analyzed from the sequentially generated characteristic X-rays, and the analysis data for each of the sequentially analyzed patterns is compared. A method of inspecting the semiconductor device for determining whether there is an abnormality in the pattern and the presence or absence of foreign matter. 2. A semiconductor device inspection apparatus for inspecting a semiconductor device having a plurality of minute patterns formed on a substrate for abnormality of the pattern and presence / absence of foreign matter adhering to the pattern. A stage to be installed; a driving unit capable of controlling position coordinates of the stage; an electron gun for generating an electron beam; and X-ray detection means for detecting characteristic X-rays generated by irradiating the pattern with the electron beam. Analyzing means for analyzing compositional elements of the pattern from characteristic X-rays detected by the X-ray detecting means; and comparing the plurality of analysis data analyzed by the analyzing means to determine whether there is an abnormality in the pattern and the presence or absence of foreign matter. A semiconductor device inspection apparatus, comprising: 3. An X-ray tube for generating X-rays is provided in place of the electron gun, and the X-ray detecting means detects characteristic X-rays generated by irradiating the pattern with X-rays generated by the X-ray tube. 3. The inspection apparatus for a semiconductor device according to claim 2, wherein the inspection is performed. 4. The inspection apparatus for a semiconductor device according to claim 2, wherein the operation mechanism of the drive unit that controls the position coordinates of the stage is configured by a piezo element that moves the stage up and down.