JPH10153603A - Method for detecting minute foreign matter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for detecting minute foreign matter, which can efficiently detect the existing position of the minute foreign matter on the plane of a sample such as a silicon wafer in a short time and can selectively measure the three-dimensional shape of that part. SOLUTION: The position where irregular reflection has occurred is detected by projecting beam light 8 on a sample surface and observing the position from a dark visual field part or a bright visual field part by a microscope 16, whose focal point is focused on the spot part. The coordinates (x1 and y1 ) are registered in an x-y actuator 12. The sample or a probe is moved by the difference between the coordinate and the position (x0 and y0 ) of the probe of the scanning probe microscope, and the three-dimensional shape of a minute foreign matter 11 is measured. Furthermore, the position of the minute foreign matter 11 is obtained beforehand by a particle detecting device. The spot irradiation of the beam light 8 is performed in the range, wherein the deviation of the coordinates from the scanning probe microscope is considered. Thus, the efficiency of the detection and inspection is enhanced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for detecting the position of a minute foreign substance present on a planar sample surface such as a silicon wafer or a glass substrate for a liquid crystal display device.
More specifically, the existence position of the minute foreign matter detected and located by the particle inspection device whose coordinates are defined in advance is coordinated with the coordinates of another analysis device such as a scanning probe microscope, and the identified position is identified. Detection and inspection methods for small foreign matter, including its three-dimensional shape, so that it can be easily observed, analyzed, inspected, and evaluated, and other analysis such as scanning probe microscopes with additional functions The present invention relates to an apparatus and a method for manufacturing a semiconductor element or a liquid crystal display element using the same.

[0002] The term "fine foreign matter" as used herein means not only adhered particles protruding from the surface of a sample, but also abnormal portions of the surface of the sample including depressions and crystal defects on the surface of the sample. Further, another analysis apparatus such as a scanning probe microscope is an atomic force microscope (AF).
M), observation devices such as scanning tunneling microscopes (STM) and magnetic force microscopes (MFM), analyzers, inspection devices,
Refers to an evaluation device.

[0003]

2. Description of the Related Art It is said that the yield in the manufacture of an ultra-highly integrated LSI typified by a 4M or 16M bit DRAM is largely influenced by a defect caused by a foreign matter attached to a wafer.

[0004] As the pattern width becomes finer,
This is because a foreign matter of a minute size, which has not been a problem in the past, adheres to the wafer in the manufacturing process in the previous step and becomes a contamination source. It is generally said that the size of the minute foreign matter causing this problem is a fraction of the minimum wiring width of the ultra-high integration LSI to be manufactured. 5 μm), a minute foreign substance having a diameter of 0.1 μm is targeted. Such a minute foreign substance becomes a contaminant, causing disconnection or short circuit of the circuit pattern, etc., and leads to the occurrence of a defect and a decrease in quality and reliability. Therefore, it is a key point for improving the yield to quantitatively and accurately measure and analyze the actual state of the attached state of the minute foreign matter and the like to grasp and manage it.

As a means for performing this, a particle inspection apparatus capable of detecting the position of a minute foreign substance present on the surface of a planar sample such as a silicon wafer has been used. In addition, as a conventional particle inspection device,
Product name; IS-2, manufactured by Hitachi Electronics Engineering Co., Ltd.
000, LS-6000 or Tencor Corp., USA; trade name; Surfscan 6200, Estek Corp., trade name; WIS-9000. The measurement principle used for these particle inspection devices and the device configuration for realizing it are described in, for example, literatures.
"Analysis and Evaluation Technology for High Performance Semiconductor Processes", 111-
This is described in detail on page 129, edited by Semiconductor Technology Research Group, published by Realize Inc.

FIG. 11 shows a particle inspection apparatus LS-60.
10 shows a display screen of a CRT showing a result of measurement of minute foreign substances (0.1 μm or more) actually present on a 6-inch silicon wafer by using 00. In other words, this display screen shows only the approximate position and the number of minute foreign substances for each size and the particle size distribution thereof. The circle shown in FIG. 11 represents the outer periphery of the 6-inch silicon wafer, and points present therein correspond to positions where minute foreign matters exist.

However, as can be seen from FIG. 11, the information obtained from the conventional particle inspection apparatus is only the size of the minute foreign matter present on the sample surface such as a silicon wafer and the existing position on the sample surface. It is not possible to identify the actual state of the minute foreign matter.

Further, conventionally, a scanning probe microscope such as an atomic force microscope or a scanning tunnel microscope having a high resolution has been used to observe a three-dimensional fine shape of a planar sample surface such as a silicon wafer. ing.

In an atomic force microscope (AFM), a pyramid-shaped protruding probe made of Si ₃ N ₄ or the like formed at the tip of a cantilever is brought close to the surface of a sample, and works between the sample and the probe. Atomic force (van der Waal)
s force) is kept constant (usually about 10 ⁻⁹ N) while controlling the sample height z to scan the sample in the xy plane,
This is a device that knows the three-dimensional shape of the sample surface by monitoring the z-axis control signal at this time.

FIG. 12 shows a conventional atomic force microscope (for example, Digital Instruments (Digital I / O)) used for observing the surface of a sample such as a silicon wafer.
products (N instruments), Nanoscope
It is an explanatory view showing the basic composition of FM (NanoScope AFM).

In FIG. 12, reference numeral 1 denotes a probe used for scanning the surface of the sample 2, which is a pyramid-shaped projection made of Si ₃ N ₄ provided at the tip of the cantilever 3. When the probe 1 is moved closer to the sample 2, the cantilever bends due to repulsion caused by contact between atoms. Therefore, the magnitude of the deflection of the cantilever 3 is proportional to the magnitude of the interatomic force acting between the probe 1 and the sample 2. Cantilever 3
The deflection of the cantilever 3 is detected by using the change in the reflection direction of the deflection detection laser light 4 emitted from the light emitting element which is the laser light source 5 such as a semiconductor laser to the reflection surface of the cantilever 3 (optical lever method). ). Light reflected from the cantilever 3 is detected by a light receiving element 6 such as a photodiode. While controlling the sample height z so as to keep the deflection of the cantilever 3 constant, the xyz fine-movement element actuator 7 scans in the xy plane, thereby obtaining the 3
Measure the dimensional shape. At this time, the control signal of each axis applied to the xyz fine-movement element actuator 7 is input to the microcomputer and displayed as a three-dimensional measurement result of the sample surface after image processing.

A scanning tunneling microscope (STM) moves a metal probe very close to the sample (about 1 nm) and keeps a high level of the sample so as to maintain a constant tunnel current flowing between the sample and the metal probe. This is a device that scans the metal probe in the xy plane while controlling the z, and monitors the z-axis control signal at this time to know the three-dimensional shape of the sample surface.

FIG. 13 shows a conventional scanning tunneling microscope (for example, Digital Instruments) used for observing the surface of a sample such as a silicon wafer.
alInstruments), trade name Nanoscope ST (NanoScope ST)
It is explanatory drawing which shows the basic structure of M)).

In FIG. 13, reference numeral 21 denotes a metal probe used for scanning the surface of the sample 2, for example, a tungsten wire is used, and its tip is formed in a sharp shape by electrolytic polishing. A bias voltage is applied between the metal probe 21 and the sample 2 by the DC power supply 23.

In the three-dimensional measurement of the surface of the sample, first, the metal probe 21 to which the bias voltage is applied is brought close to the vicinity of the surface of the sample 2 by using the xyz fine movement element actuator 27, and the measurement and management is performed by the ammeter 24. A fixed amount of tunnel current flows between them. Next, while controlling the height z of the metal probe 21 so that the magnitude of the tunnel current becomes constant, the metal probe 21 is moved to x by using the xyz fine movement element actuator 27. Scan in y-plane. The control signal of each axis applied to the xyz fine movement element actuator 27 at this time is input to the microcomputer, and is displayed as a three-dimensional measurement result of the sample surface after image processing.

A conventional atomic force microscope or a scanning tunneling microscope is disclosed in, for example, “THE TRC NEWS” No. 38 (1992), issued by Toray Research Center Co., Ltd.
Jan., pp. 33-39, published by Hitachi, Ltd., "Easy to Read STM Reader" (1991).

[0017]

It is desired to identify the actual state of individual foreign matter by directly observing or analyzing the composition by using an appropriate analyzer such as a scanning probe microscope. However, looking at conventional analyzers, for example, a scanning probe microscope,
Since the probe is simply brought into contact with an arbitrary position on the surface of a sample such as a silicon wafer and scanning is performed, the apparatus observes only the state of the sample surface at the arbitrary position. Therefore, only a few existing on the surface such as silicon wafer,
In addition, it is extremely difficult to adjust the probe of a scanning probe microscope to the position where foreign matter exists, in response to the requirement to find and inspect only foreign matter such as fine crystal defects in submicron or smaller units. . For example, if the area of a 6-inch silicon wafer is compared to the area of Sado Island, the size of a foreign substance of 0.3 μm corresponds to the size of a golf ball. It is very difficult to specify and position the probe at that position. Therefore, it is almost impossible to find only foreign matter such as an arbitrary submicron unit or a fine crystal defect in a subsubmicron unit and perform three-dimensional observation. Also, even if a particle inspection device is used in advance for position detection, the position on the wafer where each minute foreign substance exists is defined by the coordinates of the particle inspection device. Is difficult. In addition, the position on the wafer where each minute foreign matter is present is used because it is defined by a pixel (usually an area of 20 μm × 200 μm) depending on the laser light integration area on the wafer of the particle inspection apparatus. There is inherently an error corresponding to the area of the pixel. Further, when a sample such as a wafer subjected to a foreign substance inspection by a particle inspection apparatus is set in an analysis apparatus such as a scanning probe microscope which is not a particle inspection apparatus, a coordinate shift error accompanying a new setting is inevitably generated. Therefore, in order to identify the actual state of a minute foreign substance, the coordinates of the particle inspection device and the coordinates of the analysis device such as a scanning probe microscope are completely linked by using some measure, and errors depending on pixels are reduced. Lose it,
Alternatively, it is necessary to eliminate an error by registering the coordinates of an analyzer such as a scanning probe microscope by newly re-detecting the position of the minute foreign matter specified by the particle inspection apparatus. For the laser beam focusing area of the conventional particle inspection apparatus, see, for example, the literature, “Analysis and Evaluation Techniques for High-Performance Semiconductor Processes”, pp. 111-129, edited by the Semiconductor Technology Research Group,
It is described in detail by Realize Inc., and is approximately 20 μm × 200 μm.

Therefore, the coordinates of the xy stage of an analyzer such as a particle inspection device and a scanning probe microscope were examined. As a result, it was found that the coordinates of the xy stage employed in most of the devices were in an xy coordinate system. In addition, how to determine the coordinate axes and the origin position of each device with respect to the wafer to be measured is
(1) The flat line direction of the orientation flat of the wafer is the x-axis (or y-axis) direction, the normal direction in the wafer plane is the y-axis (or x-axis) direction, and the outermost periphery of the wafer is y A method in which the intersection with the axis is defined as (0, y) and the intersection with the x axis is defined as (x, 0), or (2) the flat line direction of the orientation flat of the wafer is defined as the x axis (or y).
Axis), the normal direction in the wafer plane is the y-axis (or x-axis) direction, and the outermost circumference of the wafer is measured at three or more points (however, the orientation flat portion is avoided), and this is circled. Alternatively, a method of finding the center position of the wafer by applying the equation to an elliptic equation and defining it as (0, 0) is adopted.

However, in these methods, there is a difference in the surface accuracy or delicate size of the orientation flat portion or the outermost peripheral portion of each wafer, or the adjustment of the setting of the wafer on the sample table or the delicate warpage of the wafer. Inevitably, the coordinate axis and the origin position or center position are shifted for each wafer or for each setting, and as a result, between the apparatuses employing this method (between the particle inspection apparatus and the analysis apparatus such as the scanning probe microscope). Inevitably, the coordinate axes and the origin positions of the individual wafers are shifted. Therefore, for the amount of deviation generated for the above-described reason, when a plurality of wafers in which a grid-like pattern was cut were used to investigate various devices,
High-precision equipment (Hitachi Electronics Engineering Co., Ltd.)
, Particle inspection device, trade name; IS-2000 and Hitachi, Ltd., measuring SEM, trade name; S-700
Even in the case of (0), it has been found that in the xy coordinate display, there is a deviation amount of approximately (± 100 μm, ± 100 μm) with respect to the origin position or the center position and any point that can be defined therein. Therefore, when observing or analyzing micro foreign matter at an arbitrary position on the wafer detected by the particle inspection device using an analysis device such as a scanning probe microscope, and evaluating it, at least using the particle inspection device. Centering on the position where the minute foreign matter to be detected is present (± 100 μm, ± 100
μm) or more (200 μm × 200)
μm = 40000 μm ² ), by observing using an analyzer such as a scanning probe microscope, confirming the position of the minute foreign matter, and then expanding the portion by any method such as enlarging the minute foreign matter. It is necessary to observe or analyze foreign matter. Therefore, it takes considerable time.

Now, an attempt will be made to understand what the size of this area is for a small foreign matter. Currently, 1 million pixel CC which is considered to have relatively high resolution
This 40000 μm ² (200 μm × 200
Assuming that the range of [mu] m) has been observed, the detection range (area) occupied by one pixel of the CCD camera is calculated, and the size of the smallest minute foreign matter that can be detected is considered. Detection range occupied by one pixel in the conditions of said, 0.04μm ² (4 million in [mu] m ² ÷ 100 million to calculate =
0.2 μm × 0.2 μm). On the other hand, since it is difficult to identify an object having a size smaller than one pixel, the detection limit of a minute foreign substance is 0.04 μm ² (0.2 μm × 0.2 μm).
Becomes That is, it is difficult to directly detect a minute foreign matter having a projected area of 0.04 μm ² or less (diameter of about 0.2 μm) using a CCD camera having 1 million pixels.
It seems almost impossible to determine its location.

From the above, it is known that, for a minute foreign matter having a diameter of about 0.2 μm or less conventionally detected by a particle inspection apparatus, the coordinates of an analysis apparatus such as a scanning probe microscope are used based on the coordinates of the particle inspection apparatus. It seems to be understood that it is difficult to identify the position of the minute foreign matter and directly observe or evaluate the minute foreign matter by linking with.

The present invention has been made in order to solve such a problem, and an object of the present invention is to provide a method for detecting a minute foreign matter that can easily find a position where a minute foreign matter exists on a sample surface.

[0023]

According to the present invention, there is provided a method for detecting minute foreign matter, which comprises irradiating a sample surface with a light beam for detecting minute foreign matter, and observing a change in the light beam caused by the minute foreign matter. It is characterized by detecting the position of the minute foreign matter in the xy plane.

The use of a laser beam as the beam light can enhance the directivity of the light, increase the contrast ratio, which is the change in the beam light due to the foreign matter, ensure that the foreign matter is observed, and accurately determine the position of the foreign matter. It is preferable because it can be specified.

In order to observe the change in the light beam, irregularly reflected light of the light beam is detected from a dark field portion of the light beam, or a dark portion of the light beam is detected from a bright field portion of the light beam. It can be done by doing.

The observation of the change of the light beam can be performed by focusing a microscope on the light beam spot on the surface of the sample or by making a light receiving element face the light beam spot. In addition, the detection can be performed reliably.

According to the present invention, the existence position of the minute foreign matter is detected by detecting the change of the foreign matter detection beam light applied to the sample surface on the sample surface from the dark field portion or the bright field portion. . For example, when the sample is moved in the xy plane while observing the beam spot from the dark field part,
When there is no foreign matter at the irradiation position, all the light beams are regularly reflected, and no irregularly reflected light is observed from the dark field portion. On the other hand, when a foreign substance is present, the beam light is irregularly reflected in a form depending on its size, so that irregularly reflected light is observed from the dark field portion. In this case, even if the size of the foreign matter is considerably smaller than the size of the spot portion of the sample surface where the beam light is applied, observation can be similarly performed.
Therefore, it is not always necessary to narrow the light beam to a size equivalent to the size of the foreign matter. In addition, by increasing the size of the spot to which the light beam is applied, it is possible to increase the evaluation area on the sample from which the presence or absence of a foreign substance can be determined. As a result, it is possible to easily detect not only the submicron, but also the position (x ₁ , y ₁ ) of a sub-micron or a small foreign substance of several nm or less.

When the light beam reflected from the sample surface is detected from the bright field portion, for example, if no foreign matter is present at the irradiation position, all the light beams are regularly reflected, and the light field is reflected from the bright field portion to the inside of the spot portion. No dark area is observed. On the other hand, when foreign matter is present, the irradiated light is irregularly reflected in a form depending on the surface shape of the minute foreign matter or the like. Therefore, the optical axis of the light is distorted, and largely deviates from the optical axis of the specularly reflected light from the other mirror-like sample surface. As described above, the portion where the minute foreign matter or the like obstructs the regular reflection becomes a dark portion, and the position of the minute foreign matter of the sub-submicron level can be easily detected. The position of the dark portion inside the spot portion observed from the bright field portion coincides with the position where the minute foreign matter or the like exists. As a result, the position (x ₁ , y ₁ ) of the minute foreign matter can be easily detected by detecting the light beam reflected from the sample surface from the bright field portion.

Further, according to the present invention, when a particle inspection apparatus is used together with an analysis apparatus such as a scanning probe microscope, a sample covering a shift generated when the coordinates of each of these apparatuses is roughly linked is provided. In the range on the surface, a minute foreign substance is detected, and its existing position is newly registered as (x ₁ , y ₁ ) in the coordinates of the analyzer. Therefore, even if the deviation between the coordinates of the particle inspection apparatus and the analysis apparatus is large, the position of the minute foreign matter can be easily detected with high accuracy. For example, even if the deviation is several thousand μm, the position of the minute foreign matter detected by the particle inspection apparatus can be covered within the field of view of the microscope by using an objective lens of about 5 times. In the present invention, in order to detect the minute foreign matter by observing the change of the light beam irradiated with the spot and determine the position of the foreign matter,
The presence of the minute foreign matter, which cannot be detected by the particle inspection apparatus, on the coordinates of the analyzer can be detected and its position can be determined.

By moving the sample or the probe so that the position of the minute foreign matter coincides with the position of the probe of the scanning probe microscope, the position can be easily adjusted. Can be measured and inspected. For example, when the probe of the scanning probe microscope is brought close to the beam light irradiation position on the sample surface, the probe is irradiated with the beam light, and irregular light reflection or dark portion of the beam light is generated at the probe portion. By observing the irregularly reflected light or the dark part from the field of view, the position (x ₀ , y ₀ ) of the tip of the probe can be easily set. Even if the light beam does not strike the tip of the probe, the position of the tip of the probe can be easily known because the geometric structure of the probe is known. Therefore, the position (x ₀ , y ₀ ) on the tip of the probe
Can be set.

Next, at the probe position (x ₀ , y ₀ ) of the scanning probe microscope, the existence position (x ₁ , y ₁ ) of the minute foreign matter detected by observing the light beam from the dark field portion is represented by (x ₁ −
By moving the sample or the probe of the scanning probe microscope so as to relatively move by x ₀ , y ₁ -y ₀ ), the position of the minute foreign matter can be easily adjusted to the sample observation position. Thus, the probe of the scanning probe microscope can be brought into direct contact with the foreign matter, so that a three-dimensional image of the minute foreign matter can be easily inspected using the scanning probe microscope.

In the above-described detection of the irregularly reflected light or dark portion from the dark field portion or the bright field portion, the microscope or the light receiving element is arranged on the dark field portion or the bright field portion side, and the focus of the microscope is changed to the beam light. Alignment with the spot portion on the sample surface or by making the light receiving element face the spot portion of the light beam on the sample surface allows easy and reliable detection.

In the present invention, a semiconductor wafer or an insulative transparent substrate may be removed at every manufacturing step of a semiconductor element or a liquid crystal display element or by an inspection method to which the above-mentioned method for detecting minute foreign matter is applied to all or all of the semiconductor elements or liquid crystal display elements. Inspection of a surface such as the one described above can be improved by feeding back to the process, and defective products can be eliminated, thereby improving the yield and improving the reliability.

[0034]

【Example】

[Embodiment 1] FIG. 1 is an explanatory view showing the basic configuration of an atomic force microscope which is an example of a scanning probe microscope used in an embodiment of the method for detecting minute foreign matter according to the present invention. In FIG. 1, reference numeral 13 denotes a foreign substance 11 existing on a planar sample surface.
Is an Ar laser provided for irradiating a foreign matter detection beam light 8 for detecting the laser beam. Reference numeral 12 denotes an xy actuator provided to move the xyz fine-movement element actuator 7 on which the sample 2 is mounted in the xy plane. The cantilever 3 is connected via an AFM control system 17 to a second xy actuator 15 provided for moving the cantilever 3 in the xy plane. In the drawing, the same reference numerals as those in FIG. 12 indicate the same or corresponding parts.

As shown in FIG. 1A, a mirror-polished sample 2 (CZ (plane orientation: 100) silicon wafer manufactured by Mitsubishi Materials Silicon Corp.) was used for a surface inspection apparatus manufactured by Hitachi Electronics Engineering Co., Ltd. Using IS-2000,
A sample on the surface of the sample)
Irradiation of the foreign matter detection light beam 8 is performed using the r laser 13.
Next, the probe 1 is lowered to near the surface of the sample 2 by driving the xyz fine-movement element actuator 7 and the second xy
The actuator 15 is operated in the xy plane to irradiate the foreign matter detection beam light 8 to the vicinity of the tip of the probe 1 approximately.
The Ar laser 13 and the probe 1 are observed while observing the reflected light from the dark field portion on the r laser 13 side with a microscope 16 or a light beam change detector such as a photodiode or a phototransistor.
Adjust the positional relationship of. The coordinates indicated by the second xy actuator 15 at this time are (x ₀ , y ₀ ). In addition,
The focal position of the microscope 16 is adjusted to a position where the foreign matter detection light beam 8 on the sample 2 is reflected. When a light receiving element such as a photodiode is used instead of a microscope, the light receiving element is disposed so as to face a position on the sample 2 where the foreign matter detection beam light 8 is reflected.

Next, on the surface of the sample 2, a foreign matter detection beam light 8 is applied to the vicinity of a position where the foreign matter 11 to be observed is considered to be present (the previously observed position). FIG. 2 shows a beam irradiation position when the sample surface is irradiated with the foreign matter detection light beam 8 and the foreign matter 1 existing there.
FIG. 2 is a schematic diagram when the irregularly reflected light 10 shown in FIG. 1 is observed from a dark field using a microscope 16. In the observation system shown in FIG. 2, the observation field range A of the microscope 16 installed in the dark field portion is such that the foreign matter detection beam light 8 irradiated onto the sample 2
It is shown in a form that covers the upper spot diameter B. As shown in FIG. 2, the presence position of the foreign matter 11 inside the spot diameter B can be specified by observing the irregularly reflected light 10 with the microscope 16 because the irregularly reflected light 10 is generated on the sample 2. On the other hand, even within the same spot diameter, the portion where the foreign matter 11 does not exist cannot be observed with the microscope 16 installed in the dark field part because the beam of the detection light beam 8 is completely regularly reflected. From these facts, even if the foreign matter detection beam light 8 having a spot diameter B much larger than the foreign matter is used, the irregularly reflected light 10 due to the foreign matter 11 can be observed from the microscope 16 installed in the dark field part. The position within the spot diameter can be easily specified with high accuracy.

Note that, even if a foreign substance having a length shorter than the wavelength of the light to be used is irregularly reflected, the position where the foreign substance exists is at least one of the wavelength length of the used light.
/ 2 can be accurately specified. for that reason,
The size of the target foreign matter is not limited to submicron, but can be detected to sub-submicron or a size of several nm or less. As a result, even a very small foreign substance in a large sample can be easily and accurately specified with a measurement accuracy of a half length of the wavelength of light using the existence position of the foreign substance, and an efficient inspection is performed. be able to.

Next, the xy actuator 12 is moved to the xy
While operating in the plane, the surface of the sample 2 is similarly observed from the dark field part. If there is a foreign substance 11 on the optical path, the irregularly reflected light 10 is observed at the coordinates (x ₁ , y ₁ ) of the xy actuator 12 (see FIGS. 1B and 2).

Therefore, the xy actuator 12 or the second xy actuator 15 is changed to (x ₁ −x ₀ , y ₁ −
y ₀ ) (that is, the minute foreign matter 11 is moved to the sample observation position) and the xyz fine movement element actuator 7 is adjusted, whereby an atomic force (repulsive force) of about 10 ⁻⁹ N is applied to the probe surface on the sample surface. Thus, the measurement is performed by the atomic force microscope by observing the reflected light from the laser light source 5 with the light receiving element 6, for example.

By doing so, (x ₁ ,
The three-dimensional shape of the foreign substance 11 observed in y ₁ ) can be measured with an atomic force microscope. FIG. 3 shows an example of the measurement result. FIGS. 3A and 3B show examples of depressions made of facets on the surface of a semiconductor wafer. FIG. 3A is a plan view, FIG.
(C) is the depth profile of the foreign substance observed along the bb line and the cc line of (a), respectively. FIG.
From (c), the foreign substance 11 exists on the silicon wafer surface b
About 1400 nm in the b-line direction and about 560 in the cc-line direction
It can be seen that the pit has a maximum depth of about 300 nm.

In this embodiment, an Ar laser is used as the light source of the foreign matter detection beam light. However, since the laser light can be obtained as a highly directional beam light, the contrast of the beam spot diameter can be made clear. It is possible to accurately detect the position of even a small foreign matter, which is preferable. However, the light source of the foreign matter detection beam light is not limited to the Ar laser, and other laser light such as a semiconductor laser, or infrared light, white light, visible light, or ultraviolet light is formed into a beam by an optical lens or the like. Any light source may be used as long as it is a focused light and a beam light can be obtained. In the following embodiments, an example in which an Ar laser is used as a foreign matter detection beam light source will be described, but the present invention is not limited to this. In the case of a photodiode, it can be observed by arranging it like a CCD image element.

[Embodiment 2] FIG. 4 is an explanatory view of another embodiment using an atomic force microscope as a scanning probe microscope for explaining another embodiment of the method for detecting minute foreign matter according to the present invention. .

In this embodiment, the position of the foreign matter is detected by observing the change of the foreign matter detection beam light due to the foreign matter and the change due to the tip of the probe 1 from the bright field portion of the beam light of the Ar laser 13 with the microscope 20. Or to adjust the positional relationship between the foreign matter and the probe. The other parts are the same as those of the first embodiment, and the same reference numerals in FIG. 4 denote the same parts as in FIG. Further, the alignment of the sample 2 and the sample 2 with the probe 1 and the like were performed under the same conditions as in Example 1.

A method of detecting a change in the light beam from the bright field portion of the light beam according to the present embodiment will be described. Spot portion 18 of foreign matter detection light beam 8 irradiated on the surface of sample 2
If no foreign matter is present in the sample, the foreign matter detection beam light 8 is specularly reflected on the surface of the sample 2. Therefore, in the observation by the microscope 20 from the bright field part where the specularly reflected light beam 9 is observed, The entire surface inside the spot portion 18 is bright, and a dark portion cannot be observed. On the other hand, when a foreign substance is present in the spot portion 18, regular reflection of the beam light 8 directed to the foreign substance is prevented by the foreign substance. Therefore, when the reflected light beam 9 is observed from the bright field portion, the dark portion 19 is observed in the foreign material portion (see FIG. 4B). Therefore, the coordinates (x ₁ , y ₁ ) of the position where the dark portion 19 is observed can be known, and the xy actuator 12 or the second xy actuator 15 is set to (x ₁ -x ₀ , y ₁ −y ₀ ), align the position of the probe 1 with the foreign matter, and measure the three-dimensional shape of the foreign matter 11 with an atomic force microscope. In this embodiment, the reflected light beam 9 is observed with the microscope 20. However, any device capable of detecting a change in the light beam may be used. The light beam having a light receiving element such as a photodiode or a phototransistor opposed to the spot portion may be used. Any change detector may be used as long as it detects a change in light beam. In the case of a photodiode or the like, by arranging it like a CCD image element, it is possible to observe in a dark part.

[Embodiment 3] FIG. 5 is an explanatory view showing a basic configuration of a scanning tunnel microscope which is another example of the scanning probe microscope used in another embodiment of the method for detecting minute foreign matter according to the present invention. . In FIG. 5, reference numeral 13 denotes an Ar laser provided to irradiate a foreign matter detection beam light 8 for detecting the foreign matter 11 on the sample surface. Reference numeral 12 denotes an xy actuator provided to scan the sample 2 in the xy plane. The metal probe 21 is connected via an STM control system 28 to a second xy actuator 15 provided for moving the metal probe 21 in the xy plane.
In the figure, the same reference numerals as those used in FIG. 1 or FIGS. 12 and 13 indicate the same or corresponding parts.

As shown in FIG. 5A, the same CZ (plane orientation; 1
00) The surface of the mirror-polished sample 2 made of a silicon wafer is irradiated with foreign matter detection beam light 8 using an Ar laser 13. Next, the xyz micro-movement element actuator 27 is driven to lower the metal probe 21 to near the surface of the sample 2 and the second xy actuator 15 is operated in the xy plane, whereby the foreign matter detection beam light is emitted. Adjustment is made while observing the reflected light from the dark field portion by the microscope 16 or a light beam change detector such as a photodiode so that the light 8 is irradiated to the vicinity of the tip of the metal probe 21 approximately.
The coordinates indicated by the second xy actuator 15 at this time are (x ₃ , y ₃ ). The focal position of the microscope 16 is adjusted to a position where the foreign matter detection light beam 8 is reflected on the surface of the sample 2. When a photodiode is used in place of the microscope, the photodiode is arranged so as to face the position on the sample 2 where the foreign matter detection light beam 8 is reflected.

Next, a foreign matter detection light beam 8 is irradiated on the surface of the sample 2 near a position where the foreign matter 11 to be observed is considered to be. At this time, if there is no foreign matter 11 on the optical path, the foreign matter detection beam light 8 is specularly reflected on the surface of the sample 2, so that the reflected laser light 9 from the dark field part cannot be observed. Next, while operating the xy actuator 12 in the xy directions, the surface of the sample 2 is observed from the dark field portion as in the first embodiment. If there is a foreign substance 11 in the optical path, xy
The irregularly reflected light 10 is observed at the coordinates (x ₄ , y ₄ ) of the actuator 12 (see FIG. 5B).

Therefore, the xy actuator 12 or the second xy actuator 15 is changed to (x ₄ −x ₃ , y ₄ −
y ₃ ) (that is, the position of the minute foreign matter 11 is moved to the sample observation position), and then the xyz micro-movement element actuator 27 is adjusted so that the metal probe 21 is brought into contact with the surface of the sample to obtain a scanning type. The measurement is performed using a tunnel microscope.

By doing so, (x ₄ ,
As for the foreign substance 11 observed in y ₄ ), the result of the three-dimensional measurement similar to the result of Example 1 was obtained.

[Embodiment 4] FIG. 6 is a view illustrating another embodiment of the method for detecting minute foreign matter according to the present invention, in which a scanning tunnel microscope is used as a scanning probe microscope.

In this embodiment, the position of the foreign matter can be detected by observing the change of the foreign matter detection beam light due to the foreign matter and the change due to the tip of the probe 1 from the bright field portion of the beam light of the Ar laser 13 with the microscope 20. And to adjust the positional relationship between the foreign matter and the probe. The other parts are the same as those of the third embodiment, and the same reference numerals in FIG. 6 denote the same parts as in FIG. Further, the alignment of the sample 2 and the sample 2 with the probe 1 and the like were performed under the same conditions as in Example 1.

The method of detecting a change in the light beam from the bright field portion of the light beam in this embodiment is the same as the method described in the second embodiment, and if there is no foreign matter in the spot portion 18 of the light beam 8, the microscope is used. The dark portion is not observed by the light beam change detector 20 or the like, and when a foreign object exists in the spot portion 18, the dark portion 19 is observed in the foreign object portion to know the position (x ₃ , y ₃ ) of the foreign object. Can be. In this case, the focal position of the microscope 20 is adjusted to the position where the foreign matter detection light beam 8 is reflected on the surface of the sample 2, that is, the spot portion 18, as described above. In the case of a light receiving element such as a photodiode, it is arranged so as to face the spot portion 18.

Therefore, the probe 2 of the scanning tunneling microscope is
1 and the foreign matter were aligned, and the three-dimensional shape of the foreign matter could be similarly measured.

[Embodiment 5] FIG. 7 is an explanatory diagram showing a basic configuration of an atomic force microscope which is an example of a scanning probe microscope used in another embodiment of the method for detecting a minute foreign substance according to the present invention. In FIG. 7, the output of the Ar laser 13 is 15
mW, and the light beam 8 can be polarized in each direction by the polarizing plate 33. A microscope 16 provided for observing the surface of the sample 2 irradiated with the Ar laser 13 from a dark field portion is provided with a CCD camera 31 equipped with an image intensifier.
Outputs an image at the observation position. In this embodiment, a silicon wafer is used as the sample 2. X with this
In order to move the yz fine motion element actuator 7 (which can be mounted up to an 8-inch diameter silicon wafer) in the xy plane, x-
A y actuator 12 is provided. 7, the same reference numerals as those in FIGS. 1 and 12 indicate the same or corresponding parts.

First, a plurality of mirror-polished silicon wafers 2 (CZ (plane orientation; 100), 6-inch diameter silicon wafers manufactured by Mitsubishi Materials Silicon Corporation) were subjected to a particle inspection apparatus {USA; A surf scan 6200 ° to observe an approximate size and an approximate position of the foreign matter existing on the silicon wafer 2. On the silicon wafer 2, for example, an average of 0.1 to 0.2 μm
There are about 80 foreign substances having a level diameter and about 3 foreign substances having a level diameter of 0.2 to 0.3 μm.

Next, the flat line direction of the orientation flat of the silicon wafer 2 is set as the x-axis direction, the normal direction in the wafer plane is set as the y-axis direction, and the outermost periphery of the wafer is measured at three points ( However, the orientation flat portion is avoided), and by applying this to the equation of the circle, the center position of the wafer is obtained, and by setting it to (0, 0), the silicon wafer 2 is xy.
7 is set on the fine movement element actuator 7 and FIG.
As shown in (a), the surface of the mirror-polished silicon wafer 2 is irradiated with a foreign matter detection beam light 8 using an Ar laser 13. Next, the xyz fine movement element actuator 7
To lower the probe 1 to the vicinity of the surface of the silicon wafer 2 and operate the second xy actuator 15 in the xy plane to irradiate the foreign matter detection beam light 8 to the vicinity of the tip of the probe 1. Then, from the dark field portion of the Ar laser 13 to the microscope 16
Alternatively, the positional relationship between the Ar laser 13 and the probe 1 is adjusted while observing the reflected light with a CRT 32 or the like via a photodiode or the like, and the foremost position of the probe 1 is moved to the center of the field of view of the microscope. It does not need to be set at a predetermined position within the field of view of the microscope determined in advance). The objective lens of the microscope used this time was 5 times and the eyepiece was 20 times, and the diameter of the field of view that the microscope could cover was about 2 mm. The coordinates indicated by the second xy actuator 15 at this time are (x ₀ , y ₀ ). The focus position of the microscope 16 is adjusted to a position where the foreign matter detection beam light 8 on the silicon wafer 2 is reflected. The size of the light beam was about 2 mm × 4 mm. When a photodiode is used instead of the microscope, the photodiode is arranged so as to face the position on the silicon wafer 2 where the foreign matter detection light beam 8 is reflected.

Next, the xyz micro-movement element actuator 7 is driven to move the probe 1 away from the vicinity of the surface of the silicon wafer 2.

Next, by driving the second xy actuator 15 to the position where the foreign matter detection beam light 8 is irradiated, the silicon wafer 2 for which the coordinates have been roughly observed in advance using the particle inspection apparatus Foreign matter 1 on the surface
The silicon wafer 2 is moved to a position where it is thought that there is 1 (the previously observed position).

Next, the xy actuator 12 is moved to the xy
While operating in the direction, the surface of the silicon wafer 2 is similarly observed from the dark field portion. If there is a foreign substance 11 on the optical path, x−
The irregularly reflected light 10 is observed at the coordinates (x ₁ , y ₁ ) of the y actuator 12 (see FIG. 7B).

At this time, if there is no foreign matter 11 on the optical path, the foreign matter detection beam light 8 is specularly reflected on the surface of the silicon wafer 2, so that the reflected light beam 9 from the dark field part cannot be observed. This observation state is shown in the schematic diagram of FIG. 2 and is described in the same manner as in the case of the first embodiment.

The silicon wafer 2 evaluated this time has a diameter of about 2 mm that can be covered by a microscope at a position where the foreign matter 11 seems to be present on the surface of the silicon wafer 2 which has been roughly subjected to coordinate observation using a particle inspection apparatus in advance. (1), diffused reflected light was observed at one or more locations, and rarely observed at two or more locations. Note that the intensity of the observed irregularly reflected light increases as the output of the Ar laser 13 increases,
The foreign matter having a diameter of 0.2 to 0.3 μm was stronger than the foreign matter having a diameter of 0.2 μm. The intensity of the irregularly reflected light output from the CRT 32 increased as the detection sensitivity of the CCD camera 31 equipped with the image intensifier was increased. Also, when the beam light is S-polarized light with respect to the silicon wafer surface, it becomes brightest and S
/ N was also good. Therefore, assuming that the position nm where each diffused reflection light is observed is the position where the foreign matter n is present, the position is moved to the center of the field of view of the microscope (it is not always necessary to be the center and a predetermined position within the predetermined field of view of the microscope) Position), the coordinates of the xy actuator 12 (x _n ,
registered as the location of the foreign matter n in the y _m).

Therefore, the xy actuator 12 or the second xy actuator 15 is set to (x _n −x ₀ , y _m −
y ₀ ) (that is, the minute foreign matter n is moved to the forefront position of the probe 1) and the xyz fine movement element actuator 7 is adjusted, whereby the probe 1 is moved to the surface of the silicon wafer 2 by about 10 ⁻⁹ N atoms. Contact was made so that an interforce (repulsive force) was applied, and measurement was performed with an atomic force microscope. By doing so, the three-dimensional shape of the foreign matter n observed at (x _n , y _m ) could be measured by an atomic force microscope. The observed foreign substances included various things such as a raised one and a scratch-like one.

[Embodiment 6] FIG. 8 is an explanatory view showing the basic configuration of a scanning tunneling microscope used in another embodiment of the method for detecting minute foreign matter according to the present invention. In FIG. 8, a metal probe 21 is connected to a second xy actuator 15 provided for moving the metal probe 21 in an xy plane via a control system 28 of a scanning tunneling microscope. In the drawings, the same reference numerals as those in FIGS. 1, 7, 12 and 13 indicate the same or corresponding parts.

First, the silicon wafer 2 is set on the xy actuator 12 and, as shown in FIG.
The foreign matter detection beam light 8 is irradiated using the laser 13. Next, the xyz micro-movement element actuator 27 is driven to lower the metal probe 21 to near the surface of the silicon wafer 2 and the second xy actuator 15 is operated in the xy plane, so that the foreign matter detection beam light is emitted. A CRT 32 through a microscope 16 or a photodiode from a dark field portion so that 8 is irradiated to the vicinity of the tip of the metal probe 21.
Adjust while observing diffused reflected light with a metal probe 21
Is brought to the center of the field of view of the microscope (it is not necessarily required to be at the center but may be at a predetermined position within a predetermined field of view of the microscope). The objective lens of the microscope used this time was 5 times and the eyepiece was 20 times, and the diameter of the field of view that the microscope could cover was about 2 mm. The second xy actuator 1 at this time
The coordinates indicated by 5 are (x ₃ , y ₃ ). The focal position of the microscope 16 is adjusted to a position where the foreign matter detection light beam 8 is reflected on the surface of the silicon wafer 2. When a photodiode or the like is used in place of the microscope, a position where the foreign matter detection light beam 8 on the silicon wafer 2 is reflected is provided.
The photodiodes are arranged to face each other.

Next, the xyz fine movement element actuator 2
7, the probe 21 is moved away from the vicinity of the surface of the silicon wafer 2.

Next, by driving the second xy actuator 15 to the position where the foreign matter detection light beam 8 is irradiated, the silicon wafer 2 for which the coordinate inspection has been roughly performed in advance using the particle inspection apparatus is roughly performed. Foreign matter 1 on the surface
The silicon wafer 2 is moved to a position where it is thought that there is 1 (the previously observed position).

Next, the xy actuator 12 is moved to the xy
While operating in the direction, the surface of the silicon wafer 2 is observed from the dark field portion. If there is a foreign substance, the xy actuator 12
The irregularly reflected light 10 is observed at the coordinates (x ₄ , y ₄ ) (see FIG. 8B). For the silicon wafer 2 evaluated this time, the position of the surface of the silicon wafer 2 where the foreign matter 11 seems to have been roughly observed in advance using the particle inspection apparatus is roughly within a range of about 2 mm in diameter which can be covered by the microscope. One or more irregularly reflected lights were surely confirmed in the visual field. When the polarizing plate 33 was adjusted with respect to the surface of the silicon wafer 2 to make it S-polarized, the contrast ratio was the best and the evaluation was easy. Therefore, assuming that the position nn where each diffused reflected light is observed is the position where the foreign matter n exists, the position nn is moved to the center of the visual field of the microscope, and x
-Foreign matter n at coordinates (x _nn , y _mm ) of y actuator 12
Registered as a location.

Then, the xy actuator 12 or the second xy actuator 15 is _moved to (x _nn -x ₃ , y _mm
−y ₃ ), and then adjusting the xyz micro-movement element actuator 27, so that the silicon wafer 2
The measurement is performed by a scanning tunneling microscope with the metal probe 21 approaching the surface.

By doing so, (x _nn , y
_mm ), the foreign matter n observed in 3) was the same as in Example 5.
The measurement results of the dimensional shape were obtained.

[Embodiment 7] FIG. 9 is an explanatory view showing a basic configuration of an atomic force microscope which is an example of a scanning probe microscope used in an embodiment of the method for detecting a minute foreign matter according to the present invention. In FIG. 9, a CCD camera 31 equipped with an image intensifier is attached to a microscope 20, and an image at an observation position is output by a CRT 32. 1, 4, 7 and 12 indicate the same or corresponding parts.

First, as shown in FIG. 9A, the silicon wafer 2 is set on the xyz fine-movement element actuator 7 as in the fifth embodiment, and the Ar laser 13 and the probe 1 are set in the same manner as in the fifth embodiment. Is adjusted, and the coordinates of the second xy actuator 15 when the tip end position of the probe 1 is brought to the center of the field of view of the microscope are represented by (x ₀ ,
y ₀ ). The focus position of the microscope 20 is adjusted to a position where the foreign matter detection light beam 8 is reflected on the silicon wafer 2. When a photodiode or the like is used instead of the microscope, the photodiode is arranged so as to face a position on the silicon wafer 2 where the foreign matter detection light beam 8 is reflected.

Next, the xyz fine movement element actuator 7
To move the probe 1 away from the vicinity of the surface of the silicon wafer 2.

Next, by driving the second xy actuator 15 to the position where the foreign matter detection beam light 8 is irradiated, the silicon wafer 2 for which the coordinate inspection has been roughly performed in advance using the particle inspection apparatus is roughly performed. Foreign matter 1 on the surface
The silicon wafer 2 is moved to a position where it is thought that there is 1 (the previously observed position).

Next, the xy actuator 12 is moved to the xy
While operating in the direction, the surface of the silicon wafer 2 is observed using the microscope 20 which is also set in the bright field portion. If there is a foreign substance 11 on the spot 18 where the Ar laser 13 is irradiated onto the surface of the silicon wafer 2, the light beam 8 directed to the foreign substance 11 is prevented from regular reflection by the foreign substance 11.
Therefore, when the reflected light beam 9 is observed from the bright field portion, the dark portion 19 is observed at the foreign material portion (see FIG. 9B). Therefore, the coordinates (x ₁ , y ₁ ) of the position where the dark portion 19 is observed can be known, and the xy actuator 12 or the second xy actuator 15 is set to (x ₁
−x ₀ , y ₁ −y ₀ ), the position of the probe 1 is aligned with the foreign matter, and the three-dimensional shape of the foreign matter 11 can be measured with an atomic force microscope. At this time, if there is no foreign matter 11 on the spot portion 18, the foreign matter detection beam light 8 is specularly reflected on the surface of the silicon wafer 2, so that
The dark part 19 from the bright field part cannot be observed. From these facts, even if the detection beam light 8 having a spot diameter much larger than that of the foreign matter is used, the dark part 19 can be observed by the foreign matter 11 from the microscope 20 installed in the bright field part. Can easily be specified with high accuracy.

The silicon wafer 2 evaluated this time has a diameter of about 2 mm that can be covered by a microscope at a position where the foreign matter 11 on the surface of the silicon wafer 2 has been roughly observed in advance using a particle inspection apparatus. One or more dark areas 19 were surely confirmed in the visual field in the range of (1) (in most cases, the dark areas 19 were observed in one area, and observations in two or more areas were rare). The contrast of the observed dark area was 0.1%.
0.2-0.3μm from foreign matter with level diameter of ~ 0.2μm
Foreign matter with a level diameter was stronger.

The S / N ratio was highest when the beam light 8 was converted to S-polarized light by adjusting the polarizing plate 33 with respect to the surface of the silicon wafer 2. Therefore, each dark area 19
Is assumed to be the position where the foreign matter n exists, and is brought to the center of the visual field of the microscope (it is not always necessary to be the center, but may be a predetermined position within the predetermined visual field of the microscope). ), And registered at the coordinates (x _n , y _m ) of the xy actuator 12 as the existence position of the foreign matter n.

Then, the xy actuator 12 or the second xy actuator 15 is set to (x _n −x ₀ , y _m −
y ₀ ) (that is, the minute foreign matter n is moved to the foremost position of the probe 1) and the xyz fine-movement element actuator 7 is adjusted so that the probe 1 is moved to the surface of the silicon wafer 2 by 10 ^-9 N atoms. Contact so that force (repulsive force) is applied,
The measurement was performed with an atomic force microscope. In this way, the three-dimensional shape of the foreign matter n observed at (x _n , y _m ) could be measured by an atomic force microscope as in Example 5.

[Embodiment 8] FIG. 10 is an explanatory view showing the basic configuration of a scanning tunneling microscope used in another embodiment of the method for detecting minute foreign matter according to the present invention. In FIG. 10, reference numeral 20 denotes a silicon wafer 2 irradiated with an Ar laser 13.
It is a microscope provided for observing the surface from a bright field part. A CCD camera 31 is attached to the microscope 20, and an image at an observation position is output by a CRT 32. The metal probe 21 is connected to the second xy actuator 15 via a control system 28 of the scanning tunnel microscope. In the figure, the same reference numerals as those in FIGS. 1, 4, 5, 8, and 13 indicate the same or corresponding parts.

First, a plurality of mirror-polished silicon wafers 2 were applied to a particle inspection apparatus in the same manner as in Example 5 to observe the approximate size and the approximate position of foreign matter present on the silicon wafer 2.

Next, in the same manner as in the sixth embodiment, the silicon wafer 2 is set on the xy actuator 12, and the surface of the silicon wafer 2 is detected using an Ar laser 13 as shown in FIG. A beam light 8 is applied. Next, the xyz micro-movement element actuator 27 is driven to lower the metal probe 21 to near the surface of the silicon wafer 2 and the second xy actuator 15 is operated in the xy plane, so that the foreign matter detection beam light is emitted. The microscope 8 or a CRT 32 through a photodiode or the like is used to adjust the position of the metal probe 21 so that the light 8 is approximately irradiated to the vicinity of the metal probe 21 at the front end thereof. To the center of the field of view of the microscope (not necessarily at the center, but may be at a predetermined position within a predetermined field of view of the microscope). The objective lens of the microscope used this time was 5 times and the eyepiece was 20 times, and the diameter of the field of view that the microscope could cover was about 2 mm. The coordinates indicated by the second xy actuator 15 at this time are (x ₃ , y ₃ ). The microscope 20
Is adjusted to a position where the foreign matter detection light beam 8 is reflected on the surface of the silicon wafer 2. When a photodiode or the like is used instead of the microscope, the photodiode or the like is arranged on the silicon wafer 2 so as to face the position where the foreign matter detection light beam 8 is reflected.

Next, the xyz fine movement element actuator 27
To move the metal probe 21 away from the vicinity of the surface of the silicon wafer 2.

Next, by driving the second xy actuator 15 to the position where the foreign matter detection beam light 8 is irradiated, the silicon wafer 2 for which the coordinates have been roughly observed in advance using the particle inspection apparatus can be used. Foreign matter 1 on the surface
The silicon wafer 2 is moved to a position where it is thought that there is 1 (the previously observed position).

Next, the xy actuator 12 is moved to the xy
While operating in the direction, the surface of the silicon wafer 2 is similarly observed from the bright field portion. Dark portion 19 is observed in if there is foreign matter 11 on the spot 18 of the x-y actuator 12 coordinates (x _4, y ₄₎ (see Figure 10 (b)).

The silicon wafer 2 evaluated this time has a diameter of about 2 mm that can be covered by a microscope at a position where the foreign matter 11 on the surface of the silicon wafer 2 has been roughly observed in advance using a particle inspection apparatus. One or more dark areas 19 were surely confirmed in the visual field in the range of. When the polarizing plate 33 was adjusted with respect to the surface of the silicon wafer 2 to obtain S-polarized light, the contrast ratio was the best and the evaluation was easy. Therefore, each dark area 19
Is assumed to be the position where the foreign matter n exists, and the position is taken to the center of the visual field of the microscope, and registered as the position where the foreign matter n exists at the coordinates (x _nn , y _mm ) of the xy actuator 12. .

Then, the xy actuator 12 or the second xy actuator 15 is _moved to (x _nn -x ₃ , y _mm
−y ₃ ), and thereafter, by adjusting the xyz fine motion element actuator 27, the metal probe 21 is brought into contact with the surface of the silicon wafer 2, and measurement is performed by a scanning tunneling microscope.

By doing so, (x _nn , y
_mm ), the foreign matter n observed in 3) was the same as in Example 5.
The result of the dimension measurement was obtained.

[Embodiment 9] This embodiment is an embodiment of a method for manufacturing a semiconductor device, in which foreign substances on the surface of a semiconductor wafer are inspected in the semiconductor device manufacturing process by using the above-described atomic force microscope according to the present invention. is there.

For example, in order to form an aluminum wiring on an insulating film on the surface of a silicon wafer, an aluminum film is formed on the front surface by sputtering, for example, to a thickness of 0.05 to 0.05 mm.
A film having a thickness of about 0.5 μm is formed. After that, the approximate position where the foreign matter exists on the surface of the silicon wafer is examined by the conventional particle inspection apparatus, and the x and y coordinates thereof are examined.

Then, the silicon wafer is placed on the xy stage of the atomic force microscope by aligning the orientation flat with the center determined at three points on the circumference of the silicon wafer.

The correlation between the x and y coordinates on the xy stage of the particle inspection apparatus and the atomic force microscope is ± 100 to ± 100.
The limit is about 500 μm. The x- and y-coordinates near the x- and y-coordinates, which are the locations of the minute foreign particles examined by the particle inspection apparatus described above, are irradiated with a beam for foreign matter detection of an atomic force microscope.
The position of the minute foreign matter is accurately specified by the above-described method, and the shape thereof is measured. The x and y coordinates of the particle inspection apparatus and the atomic force microscope are ± 100 to ± 100 as described above.
Although an error of about 500 μm is generated, as described above, the spot diameter of the foreign matter detection beam light is 2000 to 5000 μm.
In the range of about m, which covers the displacement, the position of the minute foreign matter can be easily and accurately specified.

In the inspection by the conventional particle inspection apparatus, only the presence of a relatively large foreign substance was known,
It was not possible to determine whether the foreign matter adversely affected the semiconductor element. However, according to the present invention, the position of the minute foreign matter can be accurately specified, and the shape of the foreign matter can be directly known three-dimensionally with an atomic force microscope. For example, whether the foreign matter is a convex foreign matter or a concave foreign matter, The depth and width of the concave shape can be immediately known. If the wiring is formed by patterning later, the convex foreign material portion is unlikely to cause a problem, but the concave foreign material portion has no aluminum film, is thin, or has a narrow wiring width. It may cause disconnection. Therefore, it becomes an important defect depending on the depth and width. In the submicron rule, when the wiring width is 0.5 μm or less,
It is said that the presence of the above-mentioned defective portion is not preferable in terms of reliability, and the presence of a concave portion having a width of 0.1 μm or more and not less than 以上 of the film thickness is not good in reliability. Therefore, if 5% or more of the number of foreign substances checked by the particle inspection apparatus is such a concave foreign substance, it is assumed that there is a defect such as dust in the film forming process of aluminum and peeling of the film due to peeling of the dust. Give feedback and improve. Also,
Since the position of the minute foreign matter can be accurately specified, it is also possible to specify a chip accompanying the defective minute foreign matter.

In this embodiment, the inspection process after the formation of the aluminum film for forming the wiring has been described. However, various processes such as cleaning, ion diffusion, film formation process, exposure, and etching are repeated for the semiconductor element. The same can be done for each step by sampling or 100% inspection.

Further, in this embodiment, the inspection is performed by using an atomic force microscope. However, the inspection can be similarly performed by using another scanning probe microscope such as a scanning tunnel microscope in addition to the atomic force microscope.

According to the present embodiment, in the manufacturing process of a semiconductor device, minute foreign matter on a semiconductor wafer can be accurately specified, and feedback can be made to the manufacturing process for improvement and defective products can be eliminated. ,
The yield can be improved and the reliability can be further improved in the manufacture of VLSI.

Further, according to the present embodiment, it is possible to find even a minute foreign matter of 0.1 μm or less which could not be detected by the conventional particle inspection apparatus, and it is also possible to detect a further minute foreign matter near the minute foreign matter found by the particle inspection apparatus. It can be inspected, and it may be useful for investigating the cause of the generation of the minute foreign matter found in the particle inspection apparatus. [Embodiment 10] This embodiment is an embodiment of a method of manufacturing a liquid crystal display device. In the manufacturing process of the liquid crystal display device, the analysis apparatus according to the present invention described above employs an atomic force microscope on an insulating transparent substrate. This is an example of analyzing foreign matter.

That is, the liquid crystal display element is provided with a thin film transistor (hereinafter, referred to as a TFT) as a switching element of each pixel and a gate wiring, a source wiring, a pixel electrode and the like provided between each pixel on an insulating transparent substrate such as glass. The TFT substrate and the opposing substrate provided with the opposing electrode and the like are attached around the periphery with a constant gap, and the liquid crystal material is injected into the gap. With recent demands for higher definition and higher aperture ratio of liquid crystal display devices, signal wiring such as gate wiring has become narrower, gaps with pixel electrodes etc. have become narrower, disconnection of signal wiring and short-circuit between wiring, etc. Is more likely to occur.

In the present invention, various processes such as a film forming process, an exposure process, and an etching process are performed in the manufacturing process of the TFT substrate. For example, in order to form a gate electrode and a gate wiring, tungsten is formed on the entire surface of the insulating transparent substrate. After a metal film such as that described above was formed to a thickness of about 0.1 to 1 μm, foreign substances on the film formation surface were inspected and analyzed using an atomic force microscope.

As in the case of a semiconductor wafer, a rough position where foreign matter is present on the film formation surface is examined by a particle inspection apparatus. Next, the insulative transparent substrate is placed on the xy stage of the atomic force microscope with its positioning mark as a reference.

The correlation between the x and y coordinates on the xy stage of the particle inspection apparatus and the atomic force microscope is ± 100 to ± 100.
Although the limit is about 500 μm, the position of the minute foreign matter could be accurately specified by the positioning method of the present invention as in the case of the ninth embodiment.

After that, as a result of observing the foreign matter with an atomic force microscope, the three-dimensional shape could be known. As a result, the presence or absence of a foreign substance that causes a defect depending on whether the foreign substance is convex or concave, or the size or depth of the foreign substance, is fed back to the manufacturing process so that the foreign substance does not occur. be able to. In this embodiment, the analysis of the aluminum film formed line for forming the wiring has been described. However, the analysis can be performed by sampling or 100% inspection after any process such as an insulating film forming process or an etching process.

Further, in this embodiment, an atomic force microscope was used, but a scanning tunneling microscope other than the atomic force microscope can be used.

According to the present embodiment, in the manufacturing process of the liquid crystal display element, the minute foreign matter on the insulating transparent substrate can be accurately specified, and can be improved by feeding back to the manufacturing process. Therefore, a high yield can be obtained even in a super-resolution multi-pixel liquid crystal display element, and the reliability is improved.

In each of the above embodiments, an Ar laser was used to obtain a light beam for detecting foreign matter. However, the present invention is not limited to an Ar laser. Any light obtained by focusing white light, visible light, or ultraviolet light into a beam with an optical lens or the like may be used. Although the sample (silicon wafer) 2 is moved by the xy actuator 12, the probe side of the microscope may be moved by the second xy actuator, and the positioning may be relatively performed. Further, in each of the above embodiments, the position of the first probe is obtained by providing the second xy actuator, but if the position of the first probe is measured while the position of the probe is fixed, A second xy actuator is not required. Further, other components other than the above description have the same configuration as that of the conventional atomic force microscope or scanning tunnel microscope, and can be changed as long as the function is exhibited.

In Examples 5 to 8, a silicon wafer is described as an example of the sample 2. However, other planar substrates such as an insulating transparent substrate (the surface may have some irregularities) can be similarly used. Is obtained, and the sample 2 is not necessarily limited to the silicon wafer.

[0105]

As described above, the present invention irradiates the sample surface with the detection beam light for detecting foreign matter, and also generates the irregularly reflected light or dark portion from the sample surface in the dark field portion or the bright field portion. For example, by detecting with a light beam change detector such as a microscope or a photodiode, the position of the minute foreign matter is found, and the position of the tip of the scanning probe microscope and the position of the minute foreign matter are relatively determined. Therefore, the probe of the scanning probe microscope can be brought into contact with only the minute foreign matter. Further, even when a particle inspection device is used in combination with the particle inspection device for detecting minute foreign matter, even if a deviation of several thousand μm occurs when the coordinates of the particle inspection device and the coordinates of the analysis device are linked, this is covered. By observing the change in the beam light spot-irradiated on the area on the sample surface, the presence of the minute foreign matter can be detected, and the position can be determined on the coordinates of the analyzer.

Even a minute foreign substance that cannot be detected by the particle inspection apparatus can be detected by the scanning probe microscope of the present invention, and leakage of the detection can be prevented.

Therefore, a minute foreign matter can be easily detected in a wide sample, and three-dimensional measurement can be selectively performed only in a range where the minute foreign matter exists. The quality of the sample can be evaluated at an early stage.

Further, according to the present invention, since fine foreign substances on a semiconductor wafer or an insulating transparent substrate can be accurately grasped and corresponding processing can be performed, defects can be prevented even in a fine pattern of submicron or less, and integration can be prevented. The yield can be improved even in an VLSI having a very high degree of reliability, and defects that become defective during use can be prevented, so that the reliability is greatly improved.

[Brief description of the drawings]

FIG. 1 is a view for explaining one embodiment of a method for detecting a minute foreign substance according to the present invention, and is an explanatory view showing a basic configuration of an atomic force microscope.

FIG. 2 is a schematic diagram when irregularly reflected light of a light beam due to a foreign substance is observed from a dark field portion.

FIG. 3 is a view showing an image of a foreign substance measured by an atomic force microscope by applying the method for detecting a minute foreign substance according to the present invention;
(A) is an AFM image, (b) and (c) are depth profiles of the foreign matter observed along the bb line and the cc line, respectively, of (a).

FIG. 4 is a view for explaining another embodiment of the method for detecting a minute foreign substance according to the present invention using an atomic force microscope.

FIG. 5 is a view for explaining another embodiment of the method for detecting minute foreign matter of the present invention, and is an explanatory view showing a basic configuration of a scanning tunneling microscope.

FIG. 6 is a view for explaining still another embodiment of the method for detecting minute foreign matter of the present invention using a scanning tunneling microscope.

FIG. 7 is a view for explaining another embodiment of the method for detecting minute foreign matter according to the present invention, and is an explanatory view showing a basic configuration of an atomic force microscope.

FIG. 8 is a view for explaining an embodiment of the method for detecting minute foreign matter according to the present invention, and is an explanatory view showing a basic configuration of a scanning tunneling microscope.

FIG. 9 is a view for explaining still another embodiment of the method for detecting minute foreign matter of the present invention using an atomic force microscope.

FIG. 10 is a view for explaining still another embodiment of the method for detecting micro foreign matter according to the present invention using a scanning tunneling microscope.

FIG. 11 shows an example of a result of measurement of a minute foreign substance on a silicon wafer by the particle inspection device LS-6000.

FIG. 12 is an explanatory diagram showing a basic configuration of a conventional atomic force microscope.

FIG. 13 is an explanatory diagram showing a basic configuration of a conventional scanning tunneling microscope.

[Explanation of symbols]

Reference Signs List 1 probe, 2 sample (silicon wafer), 3 cantilever, 5 laser light source, 6 light receiving element, 7 xyz micro-movement element actuator, 8 foreign matter detection beam light, 10
Diffuse reflection light, 11 foreign matter, 12 xy actuator,
13 Ar laser, 15 second xy actuator, 16 microscope, 19 dark part, 20 microscope, 21
Metal probe, 27 xyz fine actuator, 3
1 CCD camera, 32 CRT, 33 polarizing plate.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Isamu Kano 8-1-1, Tsukaguchi-Honmachi, Amagasaki-shi Mitsubishi Electric Corporation Materials and Devices Laboratory (72) Inventor Osamu Wada 8-1-1, Tsukaguchi-Honcho, Amagasaki-shi Mitsubishi Electric Machinery Co., Ltd. (72) Inventor Hiroshi Kurokawa 8-1-1, Tsukaguchi-Honcho, Amagasaki City Mitsubishi Electric Co., Ltd. Material Device Laboratories (72) Inventor Koichiro Hori 4-1-1, Mizuhara, Itami Mitsubishi Electric Corporation (72) Inventor Nobumi Hattori 4-1-1 Mizuhara, Itami-shi Mitsubishi Electric Corporation, Inc. U-S-II Development Laboratory (72) Inventor Masahiro Sekine 4-1-1 Mizuhara, Itami Mitsubishi (72) Inventor Masashi Omori 4-1-1 Mizuhara, Itami Mitsubishi Electric Corporation (72) Inventor Kazuo Kuramoto 8-1-1 Tsukaguchi Honcho, Amagasaki City Mitsubishi Electric Corporation Materials and Devices Laboratory (72) Inventor Junji Kobayashi 8-1-1 Honcho Tsukaguchi, Amagasaki City Mitsubishi Electric Machinery Co., Ltd.

Claims (6)

[Claims] 1. A sample surface is irradiated with a light beam for detecting minute foreign matter, and a change in the light beam caused by the minute foreign matter is observed to detect a position of the minute foreign matter of the sample in an xy plane. A method for detecting minute foreign matter, characterized in that: 2. The method according to claim 1, wherein the light beam is a laser beam.
The method for detecting minute foreign matter described in the above. 3. The method according to claim 1, wherein a change in the light beam is observed by detecting irregularly reflected light of the light beam from a dark-field portion of the light beam. 4. The method according to claim 1, wherein a change in the light beam is observed by detecting a dark portion of the light beam from a bright field portion of the light beam. 5. The method according to claim 3, wherein a change in the light beam is observed by focusing a microscope on the light beam spot on the sample surface. 6. The method according to claim 3, wherein a change in the light beam is observed by making a light receiving element face a spot of the light beam on the surface of the sample.