JPH1097053A - Inspection device for pattern defect - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect defects in a pattern with high sensitivity by constituting the device in such a manner that one light source is used, a transmission optical system and a reflection optical system can be switched, transmitted light and reflected light can be emitted at one time, and these light beams can be accepted by one sensor. SOLUTION: In this device, one light source is used and a transmission optical system 50 and a reflection optical system 60 can be switched. Transmitted light and reflected light can be emitted at one time and these light beams can be accepted in one imaging sensor 90. In this device, shutter functions 52, 62 to cut the transmitted light beam 51 and reflected light beam 61 can independently cut the respective beams 51, 61. By operating the shutter functions 52, 62, simultaneous irradiation of transmitted light and reflected light is possible. Therefore, the mask image can be observed by one imaging sensor 90 with the transmitted light, reflected light or both of transmitted/reflected light at one time.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a pattern defect inspection apparatus for inspecting a defect of a pattern formed on a sample of a photomask or a glass wafer used in semiconductor manufacturing.

[0002]

2. Description of the Related Art One of the major causes of a decrease in yield in the manufacture of large-scale integrated circuits (LSI) is a defect occurring in a photomask used when manufacturing a device by photolithography. For this reason,
The development of equipment for inspecting such defects has been active,
Has been put to practical use.

A conventional mask defect inspection apparatus is roughly divided into two chips on which the same pattern is drawn, each of which is observed by different detection means, and the difference between the two is compared and detected by an appropriate defect detection means. There is a method and a method of observing a chip on which a pattern is drawn by a detecting means, comparing the chip with data of pattern design by an appropriate defect detecting means, and detecting a defect.

In the former case, since two chips on which the same pattern is drawn are observed, if the same defect exists, the defect cannot be detected. However, the circuit for processing the design data has a disadvantage. There is an advantage that it is unnecessary and the device configuration is simple. However, in the latter case, since the inspection is performed based on the design data, there is an advantage that the defect detection is complete, but there is also a disadvantage that the structure is complicated.

In such a defect inspection apparatus, the resolution of an optical system has been improved, a comparison algorithm has been improved, and a method of measuring signal processing has been improved in order to detect an extremely small defect.

[0006] In the inspection apparatus developed at present, a method of irradiating a sample with appropriate light and detecting the transmitted light is generally used. In this method, a light-shielding portion (corresponding to a Cr portion) of the sample surface is used. Foreign matter such as dust adhering to the part) cannot be detected. On the other hand, inspection apparatuses having a reflection illumination optical system are often used in fields where transmitted light illumination such as a wafer pattern cannot be used.

As an example, a design data comparison method (die-to-die) for detecting a defect in a mask pattern using design data.
A description will be given of a mask defect inspection apparatus of the database type. An example of such a mask inspection apparatus is described in the literature (Jpn.
J. Appl. Phys. Vol.33 1994, pp7156-7162, Part1, N
o. 12B, December 1994), and FIG. 10 shows the inspection method and apparatus configuration.

In the inspection, a mask pattern is enlarged by using an optical system or the like, and a thin strip having a width W of about 300 μm is continuously measured (actually, the table continuously moves) as shown in FIG. And executed. Here, the inspection method will be briefly described with reference to FIG.

First, a mask 2 is placed on an XY table 1 and a pattern is radiated by an appropriate light source 3. Next, a pattern image is formed on the photodiode array 5 using the objective lens 4, and the pattern image is measured by the sensor circuit 6. This measurement data is A / D converted and sent to the comparison circuit 8 together with the position data from the position circuit 7. On the other hand, the design data of the pattern is sent from the magnetic disk device 9 to the bit developing circuit 11 through the control computer 10 to binarize the graphic data.
Sent to

In the comparison circuit 8, the binary bit pattern data is subjected to an appropriate filtering process to convert the binary pattern data into multi-level data. This is because the measurement data is in a state where the filter is actuated due to the resolution characteristics of the objective lens 4 and the aperture effect of the photodiode array 5. By performing a filter process on the design data, design data that matches the measurement data can be obtained.

The design data and the measurement data are compared according to an appropriate algorithm, and a portion where the design data and the measurement data do not match is determined as a defect. In the above method, the XY table on which the sample is mounted travels in a plane, and the entire mask is observed.

With respect to such an inspection apparatus, the inventors have
There has been proposed a pattern defect inspection apparatus which has transmission illumination and reflection illumination in mask pattern inspection, and which can be switched as required (Japanese Patent Laid-Open No. 58-58449).
issue). This pattern defect inspection apparatus indicates that more accurate defect inspection is possible by using the inspection result of each optical system by switching.

[0013] Inspection devices capable of irradiating transmitted light and reflected light at the same time and performing an inspection have recently attracted attention and have been developed, but many inspection devices have different wavelengths of transmitted light and reflected light. There are many disadvantages in a simple inspection device. That is, the defect detection rate of the defect inspection apparatus generally increases as the wavelength used is shorter and the numerical aperture of the optical system is larger. In many cases, the numerical aperture of the optics is
Since the reflected illumination and the respective detection optical systems are equal, the wavelength may determine the detection rate. Therefore, when the above-mentioned transmitted light and reflected light are simultaneously irradiated, the overall performance is governed by the difference in wavelength, that is, the detection rate using a light source having a long wavelength.

In addition, there is a difference between the detection rates of transmission and reflection. Furthermore, different wavelengths must be passed through each lens, which makes lens design and fabrication difficult. In particular, when different wavelengths are used in a short wavelength region, there is a problem that design is extremely difficult to eliminate chromatic aberration. In addition, two sensors for receiving the reflected light and the transmitted light are required to receive different wavelengths, and the subsequent signal processing circuit requires two sensors.
System is required.

Such a complicated system not only makes the apparatus extremely expensive, but also makes it extremely difficult to align the optical axes of the two wavelength optical systems, adjust the magnification, and adjust the position for observing the same place. Becomes

[0016]

As described above, in the conventional defect inspection apparatus, when inspecting the defect of the pattern of the sample using the transmitted light and the reflected light, there is a difference in the respective detection sensitivities. There were drawbacks, and the device was complicated and expensive.

The present invention eliminates such disadvantages and reduces the pattern more than using only transmitted light or only reflected light.
It is an object of the present invention to provide a pattern defect inspection apparatus which can detect a defect of a pattern with higher sensitivity and further simplifies the configuration of the inspection apparatus system.

[0018]

In order to solve the above problems, the present invention (claim 1) provides a transmission illumination optical system for guiding light from a light source and a reflection illumination system for guiding light of the same wavelength as the light source. An illumination optical system, switching means for switching light passing through the transmission illumination optical system and the reflection illumination optical system, and one or both of the switched light passing through the transmission illumination optical system and the reflection illumination optical system, or both of which are simultaneously applied to the sample. A light receiving element capable of receiving only the transmitted light, only the reflected light, or the transmitted light and the reflected light simultaneously, and a pattern image formed on the sample surface based on a signal from the light receiving element. And a pattern defect inspection apparatus comprising: means for obtaining measurement data corresponding to the pattern data; and means for detecting a pattern defect from the measurement data by a chip comparison method or a design data comparison method. That.

The present invention (claim 2) provides a transmissive illumination optical system to which light from a light source is guided, a reflective illumination optical system to which light of the same wavelength as the light source is guided, these transmissive illumination optical system and reflective illumination. Switching means for switching light passing through an optical system; means for simultaneously irradiating a sample with one or both of the switched light passing through the transmission illumination optical system and the reflection illumination optical system; and a lens of the transmission illumination optical system The ratio of the numerical aperture of the objective lens and the numerical aperture of the objective lens, and the ratio of the numerical aperture of the objective lens and the numerical aperture of the lens of the reflective illumination optical system,
Means for controlling independently according to the type of the pattern to be measured;
Only the transmitted light, only the reflected light, or a light receiving element capable of simultaneously receiving the transmitted light and the reflected light, and, based on a signal from the light receiving element, measurement data corresponding to a pattern image formed on the sample surface based on a signal from the light receiving element. From the means to obtain and this measurement data,
Patterning by chip comparison method or design data comparison method
And a means for detecting pattern defects.

The present invention (Claim 3) is characterized in that in the above-described pattern defect inspection apparatus (Claim 1 or 2), the light source of the transmission illumination optical system and the light source of the reflection illumination optical system are the same. I do.

According to the present invention (claim 4), in the above-described pattern defect inspection apparatus (claim 1 or 3), the first light amount adjusting means capable of independently adjusting the light intensity of the transmitted light transmitted through the sample. And a second light quantity adjusting means capable of independently adjusting the light quantity intensity of the reflected light reflected by the sample.

According to a fifth aspect of the present invention, in the above-described pattern defect inspection apparatus (the first to fourth aspects), a first method for storing defect information obtained by performing an inspection only with the transmission illumination optical system. Defect information storage means, second defect information storage means for storing information on defects obtained by performing inspection only with the reflected illumination optical system, and defect information stored in the first defect information storage means And information combining means for combining the defect information stored in the second information storage means.

According to the present invention (claim 6), in the above-described pattern defect inspection apparatus (claims 1 to 4), the transmitted light and the reflected light are simultaneously illuminated on the sample, and the defect information obtained by performing the inspection is obtained. Is further provided.

In the pattern defect inspection apparatus of the present invention, the wavelengths used for the transmitted light and the reflected light are the same. As a result, it is possible to solve the problem that the defect detection rates in the respective inspections are different due to different wavelengths in the related art.

Further, the number of the light receiving elements for detecting the reflected light and the transmitted light is made common and one. As a result, the sensor circuit and the subsequent signal processing circuit can be integrated into one system, and the control circuit configuration is simplified.

Further, if necessary, a part of the transmitted light and reflected light illuminating optical systems is provided with a means for adjusting the light amount. Further, by providing means for changing the ratio of the numerical aperture of the illumination lens and the objective lens of the transmission optical system and the reflection optical system, the contrast of the pattern image obtained by the reflected / transmitted light can be independently adjusted, and the mask can be adjusted. Inspection can be performed under optimal optical conditions according to the type.

According to the pattern defect inspection apparatus of the present invention having such an optical system, it is possible to detect a defect with higher sensitivity than before. According to the pattern defect inspection apparatus of the present invention configured as described above, since the same wavelength is used in reflection and transmission inspections, the detection sensitivity in each inspection becomes the same, and different wavelengths in reflection and transmission are used. The disadvantages of the conventional method used can be eliminated.

Also, since the sensors are the same, the control circuit becomes extremely simple, and the adjustments such as optical adjustment, optical axis alignment, and magnification adjustment which are problematic when wavelengths are different can be extremely simplified. it can. In addition, simultaneous transmission and reflection inspection can be performed using one sensor.
By adjusting the amount of reflected light, various inspection methods can be provided.

For example, by adjusting the amount of transmitted and reflected light, the amplitude (range) of the signal intensity in each case is adjusted.
Is the same, the signal of only the defective portion is detected, and the signal of the pattern can be erased. As a result, even with a die-to-database inspection apparatus, a new inspection that can execute an inspection without requiring a design pattern becomes possible, and an unknown inspection method can be developed. As described above, according to the present invention, a more practical defect inspection apparatus can be provided.

[0030]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, various embodiments of the present invention will be described. FIG. 1 is a diagram showing an optical system of a pattern defect inspection apparatus according to one embodiment of the present invention. In FIG. 1, first, a light beam 51 for transmission and a light beam 61 for reflection are taken out using one mercury lamp 3. In the middle of each of the light beams 51 and 61, shutter functions 52 and 62 capable of blocking the light beams independently are provided.
Further, at appropriate positions, light amount adjusting functions 53 and 63 capable of adjusting the respective light amounts are provided.

The light beam 51 from the transmission optical system 50 is condensed on the image sensor 90 through the objective lens 70 and the detection optical system 80, and forms a mask image. On the other hand, the reflection optical system 60
Can be configured by inserting a half mirror 64 between the objective lens 70 and the detection optical system 80. The half mirror 64 may be fixedly inserted at the position shown in the drawing, or may have a structure capable of being taken in and out. With such a configuration, the mask image can be observed by one sensor 90 simultaneously with the transmitted light and the reflected light or the transmitted / reflected light.

In general, even when only the transmitted light or the reflected light is measured, the mask image is not observed by one sensor 90 simultaneously with the transmitted / reflected light. . Generally, when only transmitted light is used, a sensor output as shown in FIG. 2A is obtained from a signal transmitted through the glass substrate 1 and a signal from the light-shielded portion 2. On the other hand, when only reflected light is used, the amount of light is lower than that of transmitted light, and a sensor output as shown in FIG. 2B is obtained. The signals in FIG. 2A and FIG. 2B are reversed in strength. When the same light source is used, the amount of transmitted light is usually much larger than the amount of reflected light. For this reason, it has been considered that the addition of a light beam as it is does not provide any advantage only by lowering the contrast.

However, the inventors have found from the detailed observation result of the observation image by the transmitted light and the reflected light that the possibility of the inspection by simultaneous illumination of the transmitted light and the reflected light as follows is realistic. Was.

First, the first feature of the present invention will be described. A first feature of the present invention is that a single light source can be used to switch between a transmission optical system and a reflection optical system, and that transmitted light and reflected light can be simultaneously illuminated, and that they can be connected to a single sensor. This is a mechanism that can receive light.

As shown in FIG. 1, shutter functions 52 and 6 for blocking transmitted light beam 51 and reflected light beam 61 are provided.
No. 2 has a configuration in which each of the light beams 51 and 61 can be shielded independently (in other words, it can be illuminated independently). Thus, as in the related art, the inspection using only the transmitted light and the inspection using only the reflected light can be performed using the same image sensor 90. And shutter functions 52 and 6
The operation 2 allows simultaneous illumination of transmitted light and reflected light.

On the other hand, the transmitted light illumination system 50 and the reflected illumination system 60
The light amount adjusting functions 53 and 63 that can adjust the respective light amounts are provided at appropriate positions of the light emitting devices. As mentioned above,
This is because, when the same light source is used, the amount of light obtained by the detector is usually much larger in the amount of transmitted light than in the amount of reflected light, and therefore, it is necessary to illuminate the sample with an optimal light amount ratio. . At this time, it is important to design the transmission light system 50 so that the light quantity decrease in the transmissive illumination system 50 is larger than the light quantity decrease in the reflection optical system 60.

As a matter of course, in order to prevent danger, the light source portion is provided with an interlock for turning off the power by a door sensor so that an operator may unexpectedly open the lamp house without any problem. In addition, the temperature sensor allows the power-off interlock to work in the event of an accident.

Further, the transmitted illumination optical system 50 has an image sensor 90 for accurately forming an image of the pattern on the sample surface.
A correction lens 54 that can be driven in response to a change in the thickness of the mask is incorporated. Further, in order to accurately position the sample surface at the focal position of the objective lens 70, an autofocus system 100 is provided, which has a structure capable of positioning the sample in the optical axis direction.

The half mirror 64 of the reflection optical system 60 can be moved in and out of the optical axis at right angles by the driving portion 65.
It has a structure that can cope with a decrease in the amount of light when an inspection is performed using only transmitted light. Transmission illumination optical system 50 and reflection illumination optical system 6
In the middle of 0, the σ stop changing mechanism 5 can change the ratio between the numerical aperture of each optical system and the numerical aperture of the objective lens 70.
6, 66 are provided.

The detection optical system 80 incorporates a variable power lens 81 that can change the optical magnification of the image sensor 90, so that the detection sensitivity can be switched. The observation optical system 110 is incorporated in the middle, and the ITV camera 1
11 or by visual observation, the pattern shape can be observed. The observation optical system 110 is mainly used in a review mode in which inspection is completed and a defect is confirmed.

With the above configuration, the mask image can be observed by one sensor 90 at the same time as the transmitted light and the reflected light or the transmitted / reflected light. In particular, FIG.
As shown in (a) to (c), the inspection is performed when the transmitted light is relatively large (a), when the reflected light is relatively large (b), and when the transmitted light and the reflected light are almost equal (c). The inspection can be performed, and the inspection suitable for the characteristics of the sample can be performed. In the figure, sensor signals shown by thick lines are obtained in each case. That is,
With the above-described configuration, such an inspection can be performed. In response to such a signal change, for example,
In the data comparison defect inspection, it is necessary to add black and white reversal and offset of design data in accordance with the sensor output.

Next, the second feature of the present invention will be described. A second feature of the present invention is that the simultaneous illumination of the transmitted light and the reflected light makes it difficult to perform patterning with either one of the illuminations.
This makes it possible to detect defects in the sensor with high sensitivity.

As described above, the signals obtained from the reflected light and the transmitted light are, as shown in FIGS. 2 (a) and 2 (b),
It is upside down. It is assumed that a signal created by using the above-described optical system and a signal synthesized by the same sensor are obtained so that the contrasts of the patterns obtained from the transmitted light and the reflected light are substantially equal.

As shown in FIG. 4A, a case where there is a defect a in a part of the pattern (here, a case of a pin dot defect in which a defect is present on the glass substrate 1 is considered. It has been thought that the signal of the defect obtained by the transmitted light and the reflected light is canceled out, so that no signal is output as the signal of the sensor 90. However, in reality, such is not the case, and the same defect is observed. Even Figure 4
As shown in (b), (there is a defect b in Cr,
Consider a pinhole defect), and a signal is generated at a portion corresponding to defect b. This is because the signal intensity of the defect observed with the transmitted light differs from the signal intensity of the defect observed with the reflected light. When there is a defect c such as dust on the Cr pattern, a signal as shown in FIG. 4C is naturally obtained.

Next, when a translucent defect is attached to the glass portion, it is difficult to extract a defect signal from transmitted light as shown in FIG. 5A. But,
When such a defect is observed with a reflection optical system, FIG.
As shown in FIG. 7, the signal of the translucent defect can be detected quite clearly. FIG. 5C shows a case of simultaneous illumination of transmitted light and reflected light.

FIGS. 5 (a) to 5 (c) show the results of adjusting the light quantity so as to make the contrast the same. FIG. 5 (a) 'also shows the case where the light quantity is different between the transmitted light and the reflected light.
As shown in (c) ′, the signal of the pattern portion and the signal of the defective portion can be measured.

As described above, translucent defects are easily detected by reflected light because, as shown in FIG. 6A, the amount of transmitted light is overwhelmingly strong in transmissive illumination, and interference occurs in the translucent portion. Although the influence is small, it is considered that the difference from the amount of light passing through a portion having no translucent defect is extremely small. However, in the reflected illumination, as shown in FIG. This is because the amount of light reflected on the S2 surface (semi-transparent film portion) is considered to be approximately the same as the amount of light reflected.

The light quantity loss due to the reflection from the translucent part (light does not return to the objective lens) or the change in the light quantity when there is interference of the reflected light in S1 and S2 is the reflected light in the part without translucent defect. This is because the amount of light greatly changes as compared with.
In reflection, the light passes through the same portion twice, so that the amount of light decreases more than in the case of transmission, and the light and dark may be emphasized by that amount. In addition, since there is a phase difference, interference easily occurs as described above. It is thought that it is.

Further, the edge portion of the pattern corresponds to FIG.
In the case of a tapered shape or uneven shape in the longitudinal direction of the edge as shown in (a), the reflection optical system causes a loss of light amount due to irregular reflection of the edge portion, and a pattern portion (here, formed on a glass surface). Since there is a step between the reflected light from the (Cr portion) and the reflected light from the glass portion, the phases of the respective reflected lights are different, and undershoot of the light amount is likely to occur at the boundary. So-called Cr
Although it is a pattern, the state is close to observing the phase shift mask.

Therefore, in the transmitted light, the projected shape of the pattern can be seen as shown in FIG. 7B, whereas in the reflected light, the light amount loss at the edge portion is large as shown in FIG. 7C. Therefore, a signal whose edge portion is emphasized is obtained.
If a slight amount of transmitted light is added in this state, the hatched portion becomes bright, and the edge portion can be observed more clearly.

As described above, it is concluded from the difference in the characteristics of the pattern observation in the transmitted illumination and the reflected illumination that the defect of the pattern can be sufficiently detected even with the simultaneous illumination of the transmitted illumination and the reflected illumination using the same sensor. Can be. Such a difference in characteristics can be changed by the σ stop changing mechanisms 56 and 66 which can change the ratio between the numerical aperture of each optical system and the numerical aperture of the objective lens 70 as described above. Then, it is preferable to change the σ stop changing mechanisms 56 and 66 freely according to the sample to be inspected.

FIG. 8 shows the results of experiments confirming whether or not these ideas are actually correct. FIG. 8 (a)
Shows the sensor signal intensity obtained by observing the pattern only with the transmitted light, and FIG. 8B shows the sensor signal intensity obtained by observing the pattern only with the reflected light. In FIG. 8A, a dark portion (shaded portion) indicates a Cr pattern portion, and a bright portion (no shaded portion) indicates a glass portion. Although a translucent defect exists in the glass portion surrounded by the circle A, no defect is detected at all only by the transmitted light in FIG.

On the other hand, in FIG. 8B, the glass portion is observed to be dark (oblique lines) and the pattern portion is observed to be bright (no oblique lines), but the translucent shape in the glass portion surrounded by the circle A is observed. It can be seen that a defect has been detected. Further, uneven light intensity over the entire darkened glass portion (indicated by crossing lines)
Have been observed. This indicates that the etching residue of Cr adhered to the glass portion, resulting in a translucent defect. As described above, the reflective optical system can detect such a defect.

FIG. 8C shows a result obtained by synthesizing the transmitted light and the reflected light at an appropriate light amount ratio and observing them with the same sensor.
It can be seen that the translucent defect is more clearly observed in the glass portion surrounded by the circle A shown above than in FIGS. 8 (a) and 8 (b). In addition, it can be seen that the emphasis at the edge portion is also clear. As described above, it can be seen from the actual observation results that the above-described inspection technique is appropriate.

Since the pattern defect inspection apparatus of the present invention can perform inspection using transmitted light and inspection using reflected light, four inspection modes can be set. The first mode is an inspection using only transmitted light. is there. This test is a category of the prior art. The second mode is an inspection using only reflected light. This inspection is also in the category of the prior art. However, depending on the case, a third inspection mode in which inspection of one mask is first performed only with the transmission illumination optical system, and then inspection of only the reflection illumination optical system is performed is considered. For this purpose, the apparatus includes first defect information storage means for storing information on defects obtained by inspection only with the transmission illumination optical system, and information on defects obtained by executing inspection only with the reflection illumination optical system. A second defect information storage unit for storing the defect information stored in the first defect information storage unit and an information synthesizing unit for synthesizing the defect information stored in the second defect information storage unit; In some cases, it is convenient to inspect the mask using such an apparatus.

In the apparatus shown in FIG. 9, defect information storage means 120 and 130 are required in each step, and further, a synthesis means 140 for synthesizing them and a defect information storage means 150 for storing the defect information are required. Become. This is necessary when reviewing the defective part after the inspection is completed.

As an inspection method, after the inspection of one mask of the entire mask is completed, the optical system is switched from the transmission illumination to the reflection illumination, and the inspection of the entire mask is performed again, as shown in FIG. , W = 300 μm is measured continuously (actually, the table moves continuously), and the optical system is switched from transmission illumination to reflection illumination alternately when it reaches the end to perform the inspection. There is a method of execution.

In general, the latter seems to be more convenient in terms of shortening the inspection time. Then, there is a fourth mode in which the inspection is performed by simultaneously illuminating the transmission and reflection. Although the inspection of the result of the photomask has mainly been described above, the present invention is not limited to this, and it is also possible to inspect the pattern transferred on the glass wafer. This inspection also enables the inspection of the pattern transferred on the wafer.

With the above-described optical system configuration and control circuit configuration, the pattern defect inspection apparatus can cope with various pattern inspections and can detect pattern defects with high sensitivity. Although the number of light sources is defined as one, the gist of the invention is not limited to this. As shown in FIG. 12, two light sources 3a and 3b having substantially the same wavelength may be provided. This means that transmission and reflection are almost the same. In addition, there is no problem even if the layout of each of the optical systems shown here is changed as long as the configuration does not deviate from the large purpose of forming a pattern image on the sensor.

[0060]

As described above, according to the present invention,
There is provided an inspection apparatus capable of performing an inspection by simultaneously irradiating transmitted light and reflected light. Conventionally, such an inspection apparatus has various problems. However, according to the inspection apparatus of the present invention, as a configuration of the optical system, first, a single lamp is used to transmit and transmit light beams of the same wavelength using a single lamp. The shutter function that can block each light beam independently, and the transmitted light and reflected light or transmitted / reflected light can be used to observe the mask image with one sensor at the same time, eliminating all such problems. Could be solved. As a result, a defect attached to a light-shielded portion that cannot be observed only with transmitted illumination can be observed with reflected illumination, and a translucent defect in a glass portion that has been missed with transmitted illumination alone can be detected. It has become possible to detect defects with higher sensitivity than in the case of only the above. In addition, a defect at an edge portion of a pattern can be detected with higher sensitivity than before.

Further, the pattern defect inspection apparatus of the present invention
Inspection with transmitted light and inspection with reflected light can be performed, so inspection with only transmitted light, inspection with only reflected light, inspection of one mask with only transmitted illumination optical system, and then inspection with only reflected illumination optical system Inspection mode that combines the inspection results and inspection that simultaneously illuminates transmission and reflection can be set, and the inspection that matches the inspection purpose of the mask can be selected. By using the four inspection modes, the type and shape of the defect,
Classification was facilitated, the accuracy of defect information analysis was improved due to more information than before, and a more practical inspection device could be obtained.

[Brief description of the drawings]

FIG. 1 is a diagram showing an example of an optical system according to the present invention.

FIG. 2 is a view for explaining a difference between signal outputs obtained by transmitted light and reflected light.

FIG. 3 is a diagram showing an example of a pattern observation signal that can be obtained by the optical system of the present invention.

FIG. 4 is a diagram showing that inspection can be performed by simultaneous illumination of transmitted light and reflected light.

FIG. 5 is a diagram showing that translucent defects can be detected by simultaneous illumination of transmitted light and reflected light.

FIG. 6 is a view for explaining the reason why a translucent defect can be detected by reflected light.

FIG. 7 is a diagram showing that signals at an edge portion can be enhanced by simultaneous illumination of transmitted light and reflected light.

FIG. 8 is a view showing experimental results showing that inspection can be performed by simultaneous illumination of transmitted light and reflected light.

FIG. 9 is a schematic control diagram corresponding to an inspection mode in the optical system of the present invention.

FIG. 10 is a view showing a mask pattern set on an XY table.

FIG. 11 is a diagram showing a conventional defect inspection apparatus.

FIG. 12 is a diagram showing another example of the optical system of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... 2 ... Mask 3 ... Light source 4 ... Objective lens 5 ... Photodiode array 6 ... Sensor circuit 7 ... Position circuit 8 ... Comparison circuit 9 ... Magnetic desk device 10 ... Control computer 11 ... Bit expansion circuit 50 ... Transmission optical system 51 ... Transmitting light beam 52, 62 Shutter function 53, 63 Light amount adjusting function 60 Reflecting optical system 61 Reflecting light beam 64 Half mirror 70 Objective lens 80 Detection optical system 90 Image sensor 120, 130, 150 ... Defect information storage means 140 ... Synthesis means

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Yasushi Sanada 72 Horikawa-cho, Saiwai-ku, Kawasaki-shi, Kanagawa Prefecture Inside the Toshiba Kawasaki Plant (72) Inventor Toshikazu Yoshino 75-1 Hasunumacho, Itabashi-ku, Tokyo Stock (72) Inventor Makoto Taya 75-1 Hasunumacho, Itabashi-ku, Tokyo Inside Topcon Corporation

Claims (6)

[Claims] 1. A transmission illumination optical system to which light from a light source is guided, a reflection illumination optical system to which light having the same wavelength as the light source is guided, and light passing through these transmission illumination optical system and reflection illumination optical system. Switching means, while the light passing through the transmission illumination optical system and the reflection illumination optical system is switched,
A means for simultaneously irradiating the sample with both, a light-receiving element capable of receiving only the transmitted light, only the reflected light, or the transmitted light and the reflected light at the same time, and the sample surface based on a signal from the light-receiving element. A pattern defect inspection apparatus comprising: means for obtaining measurement data corresponding to a pattern image formed thereon; and means for detecting a pattern defect from the measurement data by a chip comparison method or a design data comparison method. 2. A transmission illumination optical system to which light from a light source is guided, a reflection illumination optical system to which light having the same wavelength as the light source is guided, and light passing through these transmission illumination optical system and reflection illumination optical system. Switching means, while the light passing through the transmission illumination optical system and the reflection illumination optical system is switched,
Or means for simultaneously irradiating the sample with both, the ratio of the numerical aperture of the lens of the transmission illumination optical system to the numerical aperture of the objective lens, and the numerical aperture of the lens of the reflective illumination optical system and the numerical aperture of the objective lens A means for independently controlling the ratio according to the type of the pattern to be measured, a light-receiving element capable of receiving only the transmitted light, only the reflected light, or the transmitted light and the reflected light simultaneously, and a light-receiving element from the light-receiving element. A means for obtaining measurement data corresponding to the pattern image formed on the sample surface based on the signal; and a means for detecting a pattern defect from the measurement data by a chip comparison method or a design data comparison method. Pattern defect inspection equipment. 3. The pattern defect inspection apparatus according to claim 1, wherein a light source of the transmission illumination optical system and a light source of the reflection illumination optical system are the same. 4. A first light amount adjusting means capable of independently adjusting the light intensity of transmitted light transmitted through the sample, and a second light amount adjusting means capable of independently adjusting light intensity of reflected light reflected by the sample. 4. The pattern defect inspection device according to claim 1, further comprising a light amount adjusting unit. 5. A first defect information storage means for storing information of a defect obtained by performing an inspection only with the transmission illumination optical system, and a defect information storage means for storing a defect obtained by performing an inspection only with the reflection illumination optical system. Second defect information storage means for storing information;
5. An information synthesizing unit for synthesizing defect information stored in the defect information storage unit and defect information stored in the second defect information storage unit. The pattern defect inspection device according to any one of the above. 6. The apparatus according to claim 1, further comprising a third defect information storage unit for simultaneously illuminating the sample with the transmitted light and the reflected light, and storing defect information obtained by performing an inspection. 5. The pattern defect inspection device according to any one of items 4 to 4.