JP2000009656A - Pattern-inspecting device, pattern inspection method, record medium for storing pattern inspection program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pattern-inspecting device for reducing unneeded inspection time caused by the pattern defect of design-side data due to the inconveniences of a design data development circuit. SOLUTION: A CPU 10, measurement pattern data generation parts 2, 3, 4, 5, 6, and 7, design-side data generation parts 12 and 13, a comparison circuit 14 for comparing measurement pattern data with design-side data, a retry requirement-judging means 69, and a repeated inspection instruction means 61 are at least provided. When the retry requirement-judging means 69 judges that a pattern defect exceeding an amount being specified within a region range that is specified in advance exists during inspection, the repeated inspection instruction means 61 automatically inspects a region including the range at least for two times. Also, when there is no response from the pattern inspection device side at least for a certain amount of time (when it is recognized that a flag being provided for monitoring fails) for the CPU 10, inspection continues after returning to a normally operating location.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pattern inspection technique for inspecting a pattern defect of an object, and more particularly to a photomask used for manufacturing a semiconductor device or a liquid crystal display (LCD), or a wafer or a liquid crystal. The present invention relates to a pattern inspection device, a pattern inspection method, and a recording medium storing a pattern inspection program for inspecting a defect of an extremely small pattern formed on a substrate or the like.

[0002]

2. Description of the Related Art As represented by a gigabit DRAM, the pattern of a large-scale integrated circuit (LSI) is going from sub-quarter micron to nanometer order. One of the major causes of the reduction in the yield in the LSI manufacturing is a defect in a pattern of a photomask used when exposing and transferring an ultrafine pattern on a semiconductor wafer by a photolithography technique. In particular, with the miniaturization of LSI pattern dimensions formed on semiconductor wafers, dimensions that must be detected as pattern defects have become extremely small. For this reason, development of a pattern inspection apparatus for inspecting a defect of a photomask used when manufacturing such an LSI pattern and LSI has been actively performed.

On the other hand, with the advance of multimedia, L
The CD has a larger size of the liquid crystal substrate of 500 mm × 600 mm or more, and has a T size formed on the liquid crystal substrate.
The miniaturization of patterns such as FT is progressing. Therefore, it has been required to inspect very small pattern defects in a wide range. For this reason, there is an urgent need to develop a pattern inspection apparatus for efficiently inspecting a large area LCD pattern and a photomask used for manufacturing the large area LCD for defects in a short time.

FIG. 16 shows an example of such a pattern inspection apparatus. In this pattern inspection apparatus, a pattern formed on the sample 1 to be measured such as a photomask is inspected by enlarging it to a predetermined magnification using an optical system similar to a microscope. The pattern on the sample 1 to be measured is shown in FIG.
As shown in an elongated strip _{T 1, T 2, T 3} , is divided into ...... T _n, each of the strips _{T 1, T 2, T 3} , the continuous (in fact ...... T _n,
The pattern defect is inspected by scanning (the table moves). That is, the sample table (XYθ table) 2
A sample to be measured (photomask) 1 is placed thereon, and a pattern formed on the photomask 1 is irradiated with a beam having a size covering substantially one pixel by an appropriate light source 3 and a condenser lens 7. More specifically, as shown in FIG. 17B, the sample stage 2 is driven with a width P of one pixel, and for example, 2
A length W of 000 pixels is scanned, and is set as a unit scan. In this way, by moving sequentially one after another unit scan (every 2000 pixels), scanning the strip-T _1. Similarly, as shown in FIG. 17A, strips T ₂ , T ₃ ,
T _4, reciprocally scans the ...... T _n (scan). Therefore, if one pixel is 0.2 μm × 0.2 μm in FIG. 17B, P = 0.2 μm and W = 0.2 × 2000 = 400
μm.

[0005] As shown in FIG. 16, light transmitted through the photomask 1 is incident on the photodiode array 5 via the magnifying optical system 4. Therefore, the photodiode array 5
An optical image of the pattern is formed thereon. The pattern image formed on the photodiode array 5 is photoelectrically converted by the photodiode array 5 and outputs a measurement signal. This measurement signal is further subjected to A / D conversion by the sensor circuit 6.
It is converted and generates measurement pattern data. This measurement pattern data is input to the comparison circuit 14. On the other hand, X
The position of the photomask 1 on the Yθ table 2 is measured by the laser length measuring system 16 and input to the position circuit 15. Data indicating the position of the photomask 1 output from the position circuit 15 is also sent to the comparison circuit 14 together with the measurement pattern data.

On the other hand, pattern design data used for forming a pattern on the photomask 1 is read from a data memory 21 such as a magnetic disk to the design data development circuit 12 through the CPU 10 of the host computer. The design data development circuit 12 converts the pattern design data into binary or multi-value data, and sends this data to the comparison circuit 14 via the filter 13.

The filter 13 performs an appropriate filtering process on the sent graphic data. This is because the measurement pattern data obtained from the sensor circuit 6 is in a state where a filter has been actuated due to the resolution characteristics of the magnifying optical system 4, the aperture effect of the photodiode array 5, and the like. This is performed to match the measured pattern data. The comparison circuit 14 compares the measurement pattern data with the design data that has been subjected to an appropriate filtering process according to an appropriate algorithm. If they do not match, it determines that there is a pattern defect.

The data of the indicated pattern defect must be stored in the host computer for later review. However, when a pattern defect of a certain degree or more is pointed out, the inspection itself is terminated. Often, the configuration is such that It is for the following reasons. That is, if an upper limit is not set for the number of pattern defects, an enormous amount of data must be stored in the host computer when there are many pattern defects, which is not practical. If there are too many pattern defects, it is better to recreate the sample than to correct and improve the sample (by some means) using the huge amount of defect data stored in the host computer. This is because the efficiency is high.

[0009]

In the above-described pattern inspection apparatus, if the design data side outputs wrong data due to some malfunction, there is no problem with the sample to be inspected. The comparison circuit 14 indicates that there is a pattern defect. In addition, even if that part of the sample is reviewed later, it may be difficult to determine whether or not the desired performance is achieved. In such a case, there is a problem that the inspection must be performed again over the entire surface of the sample.

Similarly, even if the pattern inspection apparatus is locked due to some trouble, the inspection must be restarted from the beginning.

In view of the above problems, an object of the present invention is to avoid wasting inspection time even when a trouble occurs in a design-side data generation unit that generates design-side data based on design pattern data. An object of the present invention is to provide an efficient pattern inspection apparatus.

Another object of the present invention is to determine whether the result determined as a pattern defect is caused by an abnormality on the design data side,
An object of the present invention is to provide a pattern inspection apparatus capable of quickly determining whether a pattern to be measured is caused by a defect.

Still another object of the present invention is to provide an efficient pattern inspection method capable of preventing wasteful inspection time from being wasted when a trouble occurs in the process of generating design-side data based on design pattern data. Is to provide a way.

Still another object of the present invention is to quickly determine whether a result determined as a pattern defect is due to an abnormality on the design data side or a defect in a pattern to be measured. Is to provide a pattern inspection method.

Still another object of the present invention is to provide an efficient pattern inspection program capable of preventing a wasteful inspection time from being wasted when a trouble occurs in the process of generating design-side data based on design pattern data. Is to provide a recording medium in which is stored.

Still another object of the present invention is to promptly determine whether a result determined as a pattern defect is caused by an abnormality on the design data side or a defect of a pattern to be measured. Is to provide a recording medium storing a pattern inspection program.

[0017]

Means for Solving the Problems To achieve the above object, a first feature of the present invention is to provide a measurement pattern data generator for generating measurement pattern data corresponding to a pattern of a sample to be measured, and a design pattern data generator. A design-side data generator for generating design-side data based on the data, a comparison circuit for comparing the measured pattern data with the design-side data, and a retry necessity determining means for determining the necessity of repetitive inspection based on the output of the comparison circuit. A pattern inspection apparatus having repetition inspection command means for instructing a repetition inspection for a specific area specified in advance by the output of the retry necessity determination means.

Here, the "measurement pattern data generation unit"
Irradiates the pattern-formed sample with light of an appropriate wavelength, and acquires measurement data output by a light-receiving element that detects light transmitted through the sample or light reflected / scattered by the sample. An image acquisition unit that performs The “design-side data generation unit” includes a storage device (data memory) storing pattern design data used when drawing a pattern on a sample to be measured, and a pattern design data read from the storage device. At least a design data expanding circuit for expanding data for each pixel is provided. The "retry necessity determining means" determines the necessity of retry by using various "predetermined criteria" as described later, and automatically and repeatedly inspects a specific area specified in advance twice or more. A predetermined signal is repeatedly sent to the inspection command means. The "retry necessity determination means" and the "repeated inspection instruction means" may be provided with dedicated hardware, or may be realized by software using a general-purpose computer system and have predetermined functions. is there.

Further, it is preferable that the pattern inspection apparatus according to the first aspect of the present invention has a last result storage instruction means. When the same location is inspected a plurality of times by the last result storage instruction means, if only the last inspected result data is left, the capacity of the storage device can be effectively used.
Alternatively, when the same location is inspected a plurality of times by further providing a storage data selecting means, it is preferable to be able to select whether to leave all inspection result data or only the last result data. If you leave all test result data,
This is advantageous for hardware debugging.

Further, it is preferable that the pattern inspection apparatus according to the first aspect of the present invention is configured to further include an inspection hierarchy changing unit and an inspection speed changing unit. When the system that processes the design data has a hierarchical structure, if there is no response from the device side to the host computer for a certain period of time, or if an abnormality is found in the flag provided for monitoring, By the inspection hierarchy changing means, it is possible to return to the next higher hierarchical processing block and continue the inspection. Further, the means for developing the design data has an n-stage configuration (n
Is an integer greater than or equal to 1), when the comparing means for determining the presence or absence of a pattern defect does not send the design-side data required at that time from the upper stage, the inspection speed changing means reduces the speed. In this case, the circuit after the n-th stage of the expansion circuit may be operated again. Alternatively, when the number of times of re-examination exceeds the threshold value, the re-developing means may be re-developed and inspected before m stages (m is an integer of 1 ≦ m ≦ n). When the speed is reduced by the inspection speed changing means, only the system for processing the design data is operated alone, and the processing time is measured to estimate the degree to which the speed should be reduced and reflect the result. It is effective to have a function that can do this.

An inspection stripe width changing unit may be provided instead of the inspection speed changing unit. In other words, when the sample is divided into elongated strips (inspection stripes) and inspected, if the comparing means for judging the presence or absence of a pattern defect is not sent from the upper stage when the data required at that time is sent from the upper stage, The inspection stripe width may be changed by using the inspection stripe width changing unit, and the inspection may be performed again. The inspection stripe width changing means has a function of re-inspection from the state where the inspection stripe is cut back to the normal width when the inspection stripe becomes thinner than a predetermined value due to the inspection retry. Is preferred.

Further, in the pattern inspection apparatus according to the first aspect of the present invention, when the width of the inspection stripe is reduced, only the system for processing the design data is operated alone and the processing time is measured. A means for estimating the degree to which the width of the stripe should be reduced and reflecting the result may be provided.

If the number of times of re-inspection exceeds a certain value, a means for terminating the inspection of the sample may be further provided.

According to the above-described configuration of the first aspect of the present invention, it is possible to prevent a situation in which reinspection must be performed due to a malfunction of the pattern inspection apparatus. Therefore, the overall use efficiency of the pattern inspection apparatus can be improved.

A second feature of the present invention is a measurement pattern data generation step of generating measurement pattern data corresponding to a pattern of a measured sample; a design-side data generation step of generating design-side data based on the design pattern data; A step of comparing measured pattern data with design-side data; a step of judging the necessity of repetitive inspection based on the comparison; a pattern including at least a step of instructing repetitive inspection for a specific region specified in advance based on the result of the judgment It is an inspection method.

According to the pattern inspection method of the second aspect of the present invention, when trouble occurs in the process of generating design-side data based on design pattern data, unnecessary re-inspection is prevented, The inspection can be performed quickly and efficiently. Further, it is possible to quickly determine whether the result determined as a pattern defect is due to an abnormality on the design data side or a defect in the pattern to be measured.

Here, the measurement pattern data step is to irradiate the sample on which the pattern is formed with light having an appropriate wavelength and detect light transmitted through the sample or light reflected / scattered by the sample. And an image acquisition step of acquiring measurement data. In the design-side data generation step, pattern design data used when drawing a pattern on the sample to be measured is developed for each pixel. In the step of determining the necessity of the repetitive inspection, various “predetermined criteria” as described later are used. If the necessity of retry is determined, a specific area is automatically and repeatedly inspected two or more times.

Further, in the pattern inspection method according to the second aspect of the present invention, when the same portion is inspected a plurality of times, only the last inspection result data is left, so that the capacity of the storage device can be effectively reduced. Available. Alternatively, when the same location is inspected a plurality of times, it is preferable to be able to select whether to leave all the inspection result data or only the last result data. Leaving all inspection result data is advantageous for hardware debugging.

Also, when the system for processing the design data has a hierarchical structure, if there is no response from the device to the host computer for a certain period of time or an abnormality is detected in the flag provided for monitoring. In this case, it is possible to return to the next higher hierarchical processing block and continue the inspection. Further, when the design data is developed in an n-stage configuration (n is an integer of 1 or more), if the design-side data required at that time is not sent from the upper stage, the inspection speed is reduced and this n-stage Subsequent expansion may be performed again. Alternatively, if the number of times of re-inspection exceeds the threshold, m
(M is an integer satisfying 1 ≦ m ≦ n). When the inspection speed is reduced, only the system for processing the design data is operated alone, and by measuring the processing time, the degree to which the speed should be reduced can be estimated and the result can be reflected.

Instead of changing the inspection speed, the inspection stripe width may be changed. That is, in a method of dividing a sample into strips (inspection stripes) for inspection,
The data required for comparison to determine the presence or absence of pattern defects
If it is not sent from the upper stage at the required time, the inspection stripe may be narrowed and the inspection may be performed again. If the inspection stripe becomes thinner than the value specified in advance by the inspection retry, it is preferable to have a function of inspecting the inspection stripe again from a state where the inspection stripe is cut back to a normal width.

Further, in the pattern inspection method according to the second aspect of the present invention, when the width of the inspection stripe is reduced, only the system for processing the design data is operated alone and the processing time is measured. The degree to which the width of the stripe should be reduced can be estimated and the result can be reflected. Further, when the number of times of re-inspection exceeds a certain value, the inspection of the sample may be terminated halfway.

A pattern inspection program for implementing the pattern inspection method according to the second aspect of the present invention is stored in a computer-readable recording medium, and the pattern inspection program stored in the recording medium is stored in a host computer ( The CPU may read the program into a program memory constituting the system. Then, the pattern inspection program stored in the program memory can be executed by the processing control unit (CPU) of the host to realize the inspection method of the present invention. That is, a third feature of the present invention is a measurement pattern data generation step of generating measurement pattern data corresponding to a pattern of a measured sample; a design-side data generation step of generating design-side data based on design pattern data; Comparing the pattern data with the design-side data; determining the necessity of repeated inspection based on the comparison;
This is a recording medium storing a pattern inspection program including at least a step of instructing a repetitive inspection for a specific area specified in advance. Here, the “recording medium” means a medium on which a program such as a semiconductor memory such as a RAM or a ROM, a magnetic disk, an optical disk, a magneto-optical disk, or a magnetic tape can be recorded.

When the pattern inspection program stored in the recording medium according to the third aspect of the present invention is executed by the processing control unit (CPU) of the host, design-side data is generated due to a malfunction of the pattern inspection apparatus or the like. When a trouble occurs in the process, useless re-inspection can be prevented. Therefore, the pattern inspection can be performed quickly and efficiently.

In determining the retry necessity in the first to third aspects of the present invention, it is effective to use the following "predetermined criterion". Exist in the area,
Whether the number of pattern defects or the area of the pattern defect portion as a pattern defect group exceeds a threshold value; (b) whether pattern defects are adjacent to each other; (c) pattern defects are adjacent to each other. Whether the area of the pattern defect portion exceeds a certain value in the case; (d) When the sample is divided into elongated strips (inspection stripes) and inspected, whether the number of pattern defects in each inspection stripe exceeds a certain value. (E) In the case where the sample is divided into elongated strips (inspection stripes) and inspected, whether or not there is a pattern defect adjacent to each inspection stripe; and (f) the specimen is elongated and strips (inspection stripes). In the case of inspecting by dividing into two, whether or not the area of the pattern defect portion in each inspection stripe exceeds a certain value; (H) whether or not a pattern defect exists adjacent to each inspection stripe and the area of the pattern defect portion exceeds a certain value when the inspection is performed by dividing the inspection stripe into inspection strips; In the case where inspection is performed by dividing the inspection stripe into stripes, whether the number of pattern defects and the area of the defective portion in each inspection stripe exceed a certain value; the above various determination criteria can be adopted by the present invention.

The "specific area designated in advance" in the first to third aspects of the present invention may be based on, for example, a strip (inspection stripe) shown in FIG. A specific area including a plurality of unit scans shown in FIG. 17B may be selected, or another specific area arbitrarily selected. This specific area may be determined in consideration of the inspection efficiency.

[0036]

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

(First Embodiment) FIG. 1 shows a first embodiment of the present invention.
It is a typical block diagram showing the outline of the pattern inspection device concerning an embodiment. As shown in FIG. 1, a pattern inspection apparatus according to a first embodiment of the present invention includes a host computer (CPU) 10 and an observation data generation unit that generates measurement pattern data corresponding to the pattern of the sample 1 to be measured. (3, 7, 2, 4, 5, 6) and a design-side data generator (12, 13) for generating design-side data serving as an inspection reference
A comparison circuit 14 for comparing the measurement pattern data with the design-side data; a retry necessity determination unit 69 connected to the comparison circuit 14;

The observation data generating section irradiates the sample 1 with light to obtain an optical image corresponding to the pattern of the sample 1 to be measured, and obtains an optical image (3, 7, 2, 4). It comprises a photoelectric conversion unit 5 for converting an optical image into an electric signal, a sensor circuit 6 for converting a photoelectrically converted analog electric signal into measurement pattern data composed of a digital electric signal, and the like.

The sample table 2 on which the photomask 1 as a sample to be measured is placed can be moved in the X and Y directions and rotated in the θ direction by a table control circuit 11 which receives a command from a host computer (CPU) 10. A possible 3-axis (XY-θ) manipulator. The drive is controlled by an X motor in the X direction, by a Y motor in the Y direction, and by θ in the θ direction. As the X motor, the Y motor, and the θ motor, a known step motor or the like may be used. The position coordinates of the sample table 2 are measured by, for example, a laser length measuring system 16 and the output is
Sent to The position coordinates output from the position circuit 15 are fed back to the table control circuit 11.

The sample to be measured (photomask) 1 is automatically supplied onto the sample table 2 by, for example, an autoloader (not shown), and is automatically discharged after the inspection. Above the sample stage 2, a light irradiation unit including a light source 3 and a condenser lens 7 is arranged. Light from the light source 3 irradiates the photomask 1 via the condenser lens 7. Photo mask 1
Below, a signal detection unit including an enlargement optical system 4 and a photoelectric conversion unit (photodiode array) 5 is arranged. Then, the transmitted light transmitted through the photomask 1 is transmitted through the magnifying optical system 4 to a photoelectric conversion unit (photodiode array).
The light receiving surface of No. 5 is irradiated with an image. The focus of the magnifying optical system 4 is automatically adjusted by a focus adjusting device such as a piezo element. This focus adjustment device is controlled by an auto focus control circuit connected to the CPU. Focus adjustment may be monitored by a separately provided observation scope.

The photodiode array 5 as a photoelectric conversion unit is a line sensor or an area sensor provided with a plurality of optical sensors. By moving the sample stage 2 continuously in the X-axis direction, the photodiode array 5 detects a measurement signal corresponding to the pattern to be inspected on the photomask 1. The measurement signal is converted into digital data by the sensor circuit 6 and further arranged in a line buffer, and then sent to the comparison circuit 14 as measurement pattern data. It is assumed that the measurement pattern data is, for example, 8-bit unsigned data and expresses the brightness of each pixel.

Usually, this type of pattern inspection apparatus reads out these pattern data from the photodiode array 5 in synchronization with a clock frequency of about 10 to 30 MHz, performs appropriate data rearrangement, and performs a raster-scanned two-dimensional image. Treated as data.

Further, the pattern inspection apparatus according to the first embodiment of the present invention includes an input device 31 for receiving input of data and instructions from an operator, an output device 32 for outputting an inspection result, design pattern data, and the like. And a program memory 22 storing a pattern inspection program and the like. Input device 31
Is composed of a keyboard, a mouse, a light pen or a floppy disk device. The output device 32 includes a display device and a printer device.

The design-side data generator of the pattern inspection apparatus according to the first embodiment of the present invention comprises a design data development circuit 12, a filter 13, and the like. The design data development circuit 12 is connected to a data memory 21 and a program memory 22 via a data bus of the host computer 10. The data memory 21 and the program memory 22 include a magnetic disk device, an optical disk device, a magneto-optical disk device, a magnetic drum device, a magnetic tape device, and the like. The design pattern data in the data memory 21 is stored, for example, by dividing the entire inspection area into strip-shaped areas (inspection stripes). The strip-shaped design pattern data is stored in the CPU 10 of the host computer.
And sequentially transferred to the design data development circuit 12. The design pattern data is developed by the design data development circuit 12 to become design pattern image data, which is transferred to the filter 13. The filter 13 superimposes a blurring function simulating the observation optical system of the pattern inspection apparatus and the adjacent pixel interference characteristic of the sensor on the design pattern image data, and creates design-side data serving as an inspection reference. This design-side data is output from the filter 13 to the comparison circuit 14.
And compared with the measurement signal (measurement pattern data) by an appropriate comparison algorithm. Then, when the measurement signal (measurement pattern data) and the design-side data (design pattern data) are different, it is determined as a pattern defect. The retry necessity determination means 69 and the repetition inspection instruction means 61 may be provided with dedicated hardware, or may be realized by software using a computer system of a host and have predetermined functions.

FIG. 2 is a flowchart showing a basic processing flow of the pattern inspection method according to the first embodiment of the present invention. The actual inspection is performed by the same scanning method as in the related art. That is, as shown in FIG. 17 (a) already described, the inspection area of the sample is made into elongated strips T ₁ , T ₂ , T ₃ ,.
T _n , each strip (inspection stripe) T ₁ , T ₂ ,
Inspection is performed every T ₃ ,..., T _n . When data is saved when a pattern defect is found, a certain area (about 128 pixels or 256 pixels) is often handled collectively. Further, a system for processing design data performs an extremely high-speed processing, and sometimes causes an unexpected malfunction. The malfunction is often poor in reproducibility. In other words, even if a malfunction has occurred once, if it is possible to try again, it is not necessary to perform the inspection again from the beginning.

The pattern inspection method according to the first embodiment of the present invention will be described with reference to the flowchart of FIG.

(A) First, the number N of each strip (inspection stripe) shown in FIG. 17A is initialized in step S101 (N = 0).

(B) Next, in step S102, the inspection stripe number N is increased by one (N = N + 1).

(C) Next, the design data read from the data memory 21 is converted into binary or multi-valued data using the design data developing circuit 12 and developed (step S10).
3). Next, the data is subjected to a filtering process to obtain design-side data (step S104). On the other hand, as shown in FIG. 1, the photomask 1 is irradiated with light, photoelectrically converted by the photodiode array 5, and an image is obtained (step S10).
5). Further, A / D conversion is performed by the sensor circuit 6 (step S106), and measurement pattern data is obtained through a filtering process (step S107).

(D) Next, in step S108, the comparison circuit 14 compares the design-side data with the measurement pattern data to measure a pattern defect.

(E) Then, in step S109, it is determined whether or not the inspection needs to be performed again (retry). The criterion for determining the necessity of the retry includes: i) whether or not the number of pattern defects as a pattern defect group present in the target inspection stripe exceeds a threshold value; ii) adjacent pattern defects. Iii) whether the area of the pattern defect portion of the target inspection stripe exceeds the threshold value; iv) if an adjacent pattern defect exists, the area of the pattern defect portion is It is possible to use criteria such as whether or not the number exceeds a certain value; v) whether or not the number of pattern defects in the target inspection stripe and the total area of the pattern defect portions exceed a threshold value. When it is determined that the retry is necessary, the steps after step S103 and the steps after step S105 are repeated, and the pattern defect measurement is performed again (step S108). In the determination of the necessity of the retry for the second and subsequent times, in addition to the above criteria (i) to (v), v
i) whether the previous test result and the current test result are the same; vi
i) It is also determined whether the number of retries does not exceed a certain threshold. That is, if the same result is obtained even if the inspection is performed many times, the process proceeds to step S110. Also, when the number of retries exceeds a certain threshold, the process proceeds to step S110.

(F) In step S110, the inspection result of the inspection stripe N is stored or output. Then, the process proceeds to step S111, where the maximum number of stripes Nmax
It is determined whether or not N <Nmax, and step S102
Then, the inspection of the next stripe is started. If N ≧ Nmax, the inspection ends.

Here, the retry necessity determination in step S109 will be described in more detail.

[0054] criterion (a) 3 (a) and 4 (a) shows the design side data, FIG. 3
(B) and FIG. 4 (b) are measurement pattern data, FIG.
FIG. 4C and FIG. 4C show defect data obtained by the measurement in step S108. FIG. 3 (a) and FIG. 4 (a)
As shown in, due to a malfunction caused by some device,
If the design-side data becomes incorrect and it is pointed out that it is a pattern defect, there is a great possibility that another result will be obtained if the inspection is performed again. In other words, if the inspection is performed several times, and if a clearly different result is obtained, it can be estimated that this is due to a defect on the pattern inspection apparatus side. By automatically performing such estimation, it is possible to reduce waste of inspection. In other words, it is possible to prevent a waste of inspection that is pointed out as a pattern defect despite being not a pattern defect. Naturally, FIG.
In the case where the design-side data is normal as in (a) and there is an actual pattern defect in the measured pattern data as shown in FIG. 5 (b), the same result shown in FIG. Should be. Therefore, the criterion (a) is based on the number of pattern defects as a group of pattern defects existing in the target inspection stripe.

Judgment Criteria (b) When data is lost due to an abnormality on the processing side of the design data, it is conceivable that, depending on the data structure, the data is lost in a certain chunk. That is, the design-side data is shown in FIG.
In the case of (b), the defect data becomes adjacent as shown in FIG. 6C. As described above, when it is determined in step S109 that the pattern defect is adjacent, Redo the inspection stripe. Of course, if FIG. 6 (a) and FIG. 6 (b) are reversed and the sample is locally poor, there is no problem since the inspection should point to a pattern defect no matter how many times the inspection is performed. However, it takes extra inspection time as a whole, but it is considered to be sufficiently worth considering that the inspection should be restarted from scratch.

Determination Criteria (c) The following method is also effective. That is, the method is not the number of pattern defects indicated in each inspection stripe, but the area of the defective portion is calculated, and when this area exceeds the threshold value, the inspection stripe is redone. In other words, FIG.
In the case where (b) is measurement data, the defect data is shown in FIG.
(C), if the total area of the pattern defect portion in this inspection stripe exceeds a predetermined threshold value, it is determined that the defect may be due to a defect on the design data side. Then, the inspection stripe is redone. Of course, when the sample is poor, the same result is obtained even if the inspection is repeated. Here, to obtain the area of the defective portion, a simple method is to count up the number of pixels of the pattern defective portion.

Judgment criterion (d) Further, the following processing combining the criterion (b) and the criterion (c) can be considered. That is, when there is an adjacent pattern defect, the inspection stripe is redone when the total defect area in the area exceeds a predetermined threshold.

Criteria (e) Processing combining the criteria (a) and (c) is also conceivable. That is, when the number of pattern defects and the total area of defective portions of the inspection stripe exceed a predetermined threshold, the inspection stripe is re-executed.

A pattern inspection program for realizing the pattern inspection method according to the first embodiment of the present invention is stored in a computer-readable recording medium, and the pattern inspection program stored in the recording medium is used as a host. The program may be read into the program memory 22 by the computer (CPU) 10. Then, the pattern inspection program according to the first embodiment of the present invention stored in the program memory 22 can be executed by the processing control unit (CPU) 10 of the host to realize the above inspection method. Here, the recording medium is, for example, a semiconductor memory such as a RAM or a ROM, a magnetic disk, an optical disk, a magneto-optical disk,
A medium such as a magnetic tape on which a program can be recorded.

(Modification of First Embodiment) FIG.
It is a block diagram showing the outline of the pattern inspection device concerning the modification of an embodiment. The final result storage instruction means 72 is connected to the comparison circuit 14.

Normally, one inspection stripe is 1
Since the inspection is performed only once, the inspection result of the single inspection (the presence / absence of a pattern defect, the coordinates of the pattern defect when there is a pattern defect, the image data in the vicinity thereof, the reason for determining the pattern defect, etc.) can be left on the host computer. However, as described above, when the same inspection stripe is inspected many times, that is, when a retry is performed, if all the data is left, an enormous amount of result data may be generated in some cases. This may cause a situation where the data needs to be stored in the host computer, and there is a problem in operation. Therefore, when a retry is performed, it is appropriate for actual operation to leave the last result as the inspection result by the last result storage instruction means 72.

Further, as shown in FIG. 9, a storage data selection means 71 is provided, and a last result storage instruction means 72 is provided if necessary.
Alternatively, the all result storage instruction means 73 may be enabled. For example, it is better to keep all results for hardware debugging, and in such a situation, it is desirable to be able to switch freely so that all data can be kept.

The stored data selecting means 71, last result storing instruction means 72, and all result storing instruction means 73
Dedicated hardware may be prepared for each, and it may be realized by software using a general-purpose computer system and have predetermined functions.

(Other Modifications of First Embodiment) In the first embodiment of the present invention, it is determined that the process is completed even if the flag originally provided for monitoring during the inspection has passed a predetermined time. If the state shown is not reached, it may be determined that some malfunction has occurred on the pattern inspection apparatus side, and the inspection stripe may be automatically redone again. Further, when an error that should not occur in the normal operation occurs during the inspection, it may be determined that the pattern inspection apparatus side is malfunctioning, and the inspection stripe may be automatically restarted from the inspection stripe.

(Second Embodiment) FIG. 10 is a block diagram schematically showing a pattern inspection apparatus according to a second embodiment of the present invention. As shown in FIG. 10, the pattern inspection apparatus according to the second embodiment of the present invention includes a host computer (CPU) 10 and an observation data generation unit (3, 7, 2, 4, 4) for generating measurement pattern data. 5, 6), a design-side data generation unit (12, 13) for generating design-side data,
A comparison circuit 14 for comparing the measured pattern data with the design-side data; a retry necessity determination unit 69 connected to the comparison circuit 14; and a test hierarchy change unit 66 connected to the design-side data generation units (12, 13). And inspection hierarchy changing means 6
6 is provided with at least an inspection speed changing means 64 connected to the inspection speed changing means 64 and a repetitive inspection instruction means 61 connected to the inspection speed changing means 64. The repetitive inspection command means 61 is connected to the table control circuit 11 and is configured to be able to drive the table control circuit 11.

The observation data generation unit irradiates the sample 1 to be measured with light and obtains an optical image corresponding to the pattern of the sample 1 to be measured. It comprises a photoelectric conversion unit 5 for converting an optical image into an electric signal, a sensor circuit 6 for converting a photoelectrically converted analog electric signal into measurement pattern data composed of a digital electric signal, and the like. A sample table 2 on which a photomask 1 as a sample to be measured is placed can be moved in the X and Y directions and can be rotated in the θ direction by a table control circuit 11 which receives a command from a host computer (CPU) 10. . The position coordinates of the sample stage 2 are measured by, for example, a laser length measuring system 16, and the output is sent to the position circuit 15. The position coordinates output from the position circuit 15 are fed back to the table control circuit 11.

Above the sample table 2, a light irradiating section comprising a light source 3 and a condenser lens 7 is arranged. Light from the light source 3 irradiates the photomask 1 via the condenser lens 7.
Below the photomask 1, a signal detection unit including an enlargement optical system 4 and a photoelectric conversion unit (photodiode array) 5 is arranged. Then, the transmitted light transmitted through the photomask 1 is image-formed and irradiated on the light receiving surface of the photoelectric conversion unit (photodiode array) 5 via the magnifying optical system 4. The photodiode array 5 as a photoelectric conversion unit is a line sensor or an area sensor provided with a plurality of optical sensors. By moving the sample stage 2 continuously in the X-axis direction, the photodiode array 5 detects a measurement signal corresponding to the pattern to be inspected on the photomask 1. The measurement signal is converted into digital data by the sensor circuit 6 and further arranged in a line buffer, and then sent to the comparison circuit 14 as measurement pattern data.

Further, the pattern inspection apparatus according to the second embodiment of the present invention includes an input device 31 for receiving input of data and instructions from an operator, an output device 32 for outputting inspection results, design pattern data, and the like. And a program memory 22 storing a pattern inspection program and the like.

The design-side data generator includes a design data expansion circuit 12, a filter 13, and the like. The design data development circuit 12 is connected to a data memory 21 and a program memory 22 via a data bus of the host computer 10.
It is connected to the. What is stored in the data memory 21 is
The data is sequentially transferred to the design data development circuit 12 under the control of the CPU 10 of the host computer. The design pattern data is developed by the design data development circuit 12 to become design pattern image data, which is transferred to the filter 13. The filter 13 creates design-side data serving as an inspection reference by superimposing a blurring function simulating an observation optical system of a pattern inspection apparatus or an adjacent pixel interference characteristic of a sensor on the design pattern image data. The design-side data is further sent from the filter 13 to the comparison circuit 14 and compared with the measurement signal (measurement pattern data) by an appropriate comparison algorithm. Then, when the measurement signal (measurement pattern data) and the design-side data (design pattern data) are different, it is determined as a pattern defect. The inspection hierarchy changing unit 66, the inspection speed changing unit 64, the retry necessity determining unit 69, and the repetitive inspection instruction unit 61 may be provided with dedicated hardware, and are realized by software using a host computer system. It is also possible to have a predetermined function.

As shown in FIG. 11, when the design data expanding circuit 12 has multi-stage hierarchical data expanding means in accordance with the hierarchical structure of the design data, the normal processing speed is increased due to locally high data density. May be unable to deploy design data. FIG. 11 shows the first
Hierarchical data expanding means 51 and second hierarchical data expanding means 5
This is the case of two stages of 2 (n = 2). The design data development circuit 12 is composed of the first hierarchy data development means 51, the second hierarchy data development means 52, and the pattern generation means 53. If the design data cannot be developed at the normal processing speed, the design data does not come to the comparison circuit 14 when necessary, and thus an error is determined. In such a case, an instruction is issued from the inspection hierarchy changing unit 66 shown in FIG. 10 to the inspection speed changing unit 64, and the processing is performed with the processing speed on the measurement pattern data side reduced. In addition, the design data development circuit processes the lower layer processing as much as possible. By doing so, the loss of processing time can be reduced as much as possible. As a method of reducing the processing speed, it is an orthodox method that the processing speed is usually reduced from 100% at a predetermined rate such as 75% and 50%. However, once the system for processing the design data alone is idled once, it is possible to roughly estimate how fast the system can be processed to reduce the speed. If the pattern inspection apparatus is operated based on this estimated value, it is not necessary to inspect the same location many times. However,
Since a system for processing design data uses a memory in real time and may have a locally high data density, it is not possible to judge whether the data can be completely processed only by the average processing speed of the test stripe. Therefore, an estimation calculation with some margin should be performed.

FIGS. 12 and 13 are flowcharts showing a pattern inspection method according to the second embodiment of the present invention.

(A) First, the inspection speed is set in step S201, and the inspection stripe width is set in step S202. Then, the number N of each strip (inspection stripe) shown in FIG. 17A is initialized in step S203 (N
= 0).

(B) Next, in step S204, the inspection stripe number N is increased by one (N = N + 1).

(C) Next, the first of the design data
The design data read from the data memory 21 is converted into first-layer data and expanded by using the hierarchical data expansion unit 51 (step S205).

(D) The first hierarchical data is converted into the second hierarchical data by using the second hierarchical data expanding means 52 of the design data expanding circuit 12 and expanded (step S20).
6) Obtain a reference pattern (step S207). Further, filter processing is performed on the reference pattern to obtain design-side data. On the other hand, as shown in FIG.
Is irradiated with light, photoelectrically converted by the photodiode array 5, and an image is obtained (step S210). Further, A / D conversion is performed by the sensor circuit 6 (step S211), and filtered pattern data is obtained (step S212) to obtain measurement pattern data.

(E) If it is determined in step S209 that the reference pattern has not arrived by the predetermined time To, the flow advances to step S218. In step S218, the number of retries for the second hierarchy exceeds the threshold. Is determined. If the threshold is not exceeded, the process returns to step S206, and the expansion of the second hierarchy is repeated. If the threshold value is exceeded in step S218, the process proceeds to step S231 shown in FIG. Step S
At 231, it is determined whether or not the number of retries for deployment from the first hierarchy exceeds a threshold. If the threshold value is exceeded, the inspection is terminated because the inspection cannot be continued.

(F) In step S231, if the number of retries does not exceed the threshold, step S23
Step 3 changes the inspection speed. Then, step S20
Returning to step 5, the inspection by expansion from the first level is repeated.

(G) If the reference pattern arrives within the predetermined arrival time T ₀ by the expansion of the first hierarchy, the comparison circuit 14
The reference pattern is sent to (step S209). And
An image is acquired by changing the inspection speed (step 233) or changing the inspection stripe width (stripe S235) (step S210). After the A / D conversion (step S211), filter processing is performed (step S21).
2), a series of processing for sending the measurement pattern data to the comparison circuit 14 proceeds.

(H) A pattern defect is measured based on the reference pattern and the measurement pattern data sent to the comparison circuit 14 (step S213). Then, in step S214, the necessity of a retry is determined. If it is determined that a retry is necessary, the first
It is determined whether the number of retries for the tier exceeds a threshold. That is, the inspection is for the first layer, and if the number of retries is within a certain threshold value, the process returns to step S205 to retry from the first layer. On the other hand, if the number of retries for the first layer exceeds the threshold, the process proceeds to step S216, and the inspection result is stored or output.

In step S216, the inspection result of the inspection stripe N is stored or output. Then, the process proceeds to step S217, where the maximum number of stripes Nmax
It is determined whether or not N <Nmax, and step S204
Then, the inspection of the next stripe is started. If N ≧ Nmax, the inspection ends.

The pattern inspection program for realizing the pattern inspection method according to the second embodiment of the present invention is stored in a computer-readable recording medium, and the pattern inspection program stored in the recording medium is used as a host. Program memory 22 by the computer system
May be read. Then, the program memory 22
The pattern inspection program according to the second embodiment of the present invention stored in the host can be executed by the processing control unit (CPU) 10 of the host to realize the inspection method described above. Here, the recording medium is, for example, a semiconductor memory such as a RAM or a ROM, a magnetic disk, an optical disk, a magneto-optical disk,
A medium such as a magnetic tape on which a program can be recorded.

(Modification of Second Embodiment) FIG. 14 is a block diagram schematically showing a pattern inspection apparatus according to a modification of the second embodiment. The pattern inspection apparatus according to the modification of the second embodiment is different from the inspection speed changing means 64 shown in FIG.
Two.

FIG. 15 is a flowchart for explaining an inspection method according to the modification. Step S23 in FIG.
Instead of lowering the inspection speed at the time of retry as shown in FIG. 3, the width of the inspection stripe is reduced to half the normal width in the stripe S235 in FIG. In this case, the amount of data processed by the hardware is simply halved, so this method is also practical if the processing speed of the hardware is not enough. In this case, too, it is not realistic to reduce the inspection width to infinity. Therefore, a limit value is provided, and if processing cannot be performed even after that, the inspection is terminated.

Further, there is a method in which this method is taken one step further, and the inspection width at the time of retry is estimated and calculated. That is, also in this case, if the system for processing the design data is once idle-run alone, it is possible to roughly estimate how much the data amount can be reduced to complete the processing. If the pattern inspection apparatus is operated based on the estimated value, it is not necessary to cut the inspection stripe many times.

(Other Embodiments) As described above, the present invention has been described with reference to the first and second embodiments.
The discussion and drawings that form part of this disclosure should not be understood as limiting the invention. From this disclosure, various alternative embodiments, examples, and operation techniques will be apparent to those skilled in the art.

In the first and second embodiments described above, the photomask is described as the sample to be measured. However, the sample to be measured may be a semiconductor wafer or a liquid crystal substrate. When a semiconductor wafer is used as a sample to be measured, infrared light may be used as a light source, or an optical image acquisition unit configured to measure reflected light or scattered light may be used. In the case of a liquid crystal substrate as well, whether to select transmitted light or reflected / scattered light may be determined depending on the inspection content.

Also, in the flowcharts (FIGS. 2 and 12) used for the description of the first and second embodiments, the inspection is repeated for each strip (inspection stripe). Specifically, it is needless to say that the inspection may be redone for a specific area specified in advance.

As described above, the present invention naturally includes various embodiments and the like not described herein. Therefore, the technical scope of the present invention is defined only by the matters specifying the invention according to the claims that are appropriate from the above description.

[0089]

According to the present invention, an efficient pattern inspection without wasting inspection time even when a trouble occurs in a design-side data generator for generating design-side data based on design pattern data. A device can be provided.

According to the present invention, it is possible to quickly determine whether a result determined as a pattern defect is caused by an abnormality on the design data side or a defect of a pattern to be measured. An inspection device can be provided.

According to the present invention, when any trouble occurs in the process of generating design-side data based on design pattern data, such trouble can be quickly determined and the inspection time can be prevented from being wasted. It is possible to provide a method.

According to the present invention, it is possible to quickly determine whether a result determined as a pattern defect is due to an abnormality on the design data side or a defect in a pattern to be measured. A method can be provided.

According to the present invention, when a trouble occurs at the stage of generating design-side data based on design pattern data, a high-efficiency pattern inspection program capable of quickly determining such trouble and preventing useless inspection is provided. It is possible to provide a stored recording medium.

According to the present invention, it is possible to quickly determine whether a result determined as a pattern defect is caused by an abnormality on the design data side or a defect of a pattern to be measured. A recording medium storing the program can be provided.

[Brief description of the drawings]

FIG. 1 is a block diagram schematically showing a pattern inspection apparatus according to a first embodiment of the present invention.

FIG. 2 is a flowchart showing a basic processing flow of the pattern inspection method according to the first embodiment of the present invention.

FIG. 3 is a diagram for explaining a relationship among design-side data (a), measurement pattern data (b), and defect data (c) at that time when there is a pattern defect in the design-side data.

FIG. 4 is a diagram for explaining a relationship among design-side data (a), measured pattern data (b), and defect data (c) at that time when there is a pattern defect in the design-side data.

FIG. 5 shows design-side data (a), measured pattern data (b),
FIG. 9 is a diagram for explaining the relationship between defect data (c) at that time.

FIG. 6 is a diagram for explaining a relationship between measured pattern data (b) and defect data (c) at that time when data is missing as a lump in design-side data (a).

FIG. 7 is a diagram for explaining the relationship among design-side data (a), measured pattern data (b), and defect data (c) at that time when the total area of the pattern defect portion is used as a criterion for retry. is there.

FIG. 8 is a block diagram schematically showing a pattern inspection apparatus according to a modification of the first embodiment of the present invention.

FIG. 9 is a block diagram schematically showing a pattern inspection apparatus according to another modification of the first embodiment of the present invention.

FIG. 10 is a block diagram schematically showing a pattern inspection apparatus according to a second embodiment of the present invention.

FIG. 11 is a block diagram showing in detail a design data development circuit of the pattern inspection apparatus according to the second embodiment of the present invention.

FIG. 12 is a flowchart showing a basic processing flow of a pattern inspection method according to a second embodiment of the present invention (part 1).

FIG. 13 is a flowchart showing a basic processing flow of the pattern inspection method according to the second embodiment of the present invention (part 2).

FIG. 14 is a block diagram schematically showing a pattern inspection apparatus according to a modification of the second embodiment of the present invention.

FIG. 15 is a flowchart showing a part of a basic processing flow of a pattern inspection method according to a modification of the second embodiment of the present invention.

FIG. 16 is a block diagram schematically showing a conventional pattern inspection apparatus.

FIG. 17 is a schematic diagram illustrating an inspection stripe (strip) in an inspection of a photomask pattern.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Photomask (sample to be measured) 2 XYθ table 3 Light source 4 Magnifying optical system 5 Photodiode array 6 Sensor circuit, 7 Condensing lens 10 CPU 11 Table control circuit 12 Design data development circuit 13 Filter 14 Comparison circuit 15 Position circuit 16 Laser Length measuring system 21 Data memory 22 Program memory 31 Input device 32 Output device 51 First hierarchical data expanding means 52 Second hierarchical data expanding means 53 Pattern generating means 61 Repetitive inspection instruction means 62 Inspection stripe width changing means 64 Inspection speed changing means 66 Inspection hierarchy change means 69 Retry necessity determination means 71 Saved data selection means 72 Last result storage instruction means 73 All result storage instruction means

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H01L 21/66 H01L 21/30 502V (72) Inventor Tomohide Watanabe 1 Komukai Toshiba-cho, Saiwai-ku, Kawasaki-shi, Kanagawa F-term in Toshiba Tamagawa Factory (reference) BA04 BA20 CA39 DB04 DJ01 DJ14 DJ18 DJ21 DJ39

Claims (3)

[Claims] A measurement pattern data generation unit that generates measurement pattern data corresponding to a pattern of a sample to be measured; a design data generation unit that generates design data based on design pattern data; A comparison circuit for comparing design-side data; retry necessity determination means for determining the necessity of repetition inspection based on an output of the comparison circuit; And a repetition inspection command means for instructing repetition inspection of the pattern inspection apparatus. 2. A pattern inspection method comprising at least the following steps. (A) a measurement pattern data generation step for generating measurement pattern data corresponding to the pattern of the sample to be measured (b) a design-side data generation step for generating design-side data based on the design pattern data (c) the measurement pattern data Step of comparing design-side data (D) Step of determining necessity of repetitive inspection based on the comparison (E) Step of instructing repetitive inspection for a specific area specified in advance based on the result of the determination 3. A recording medium storing a pattern inspection program including at least the following steps. (A) a measurement pattern data generation step for generating measurement pattern data corresponding to the pattern of the sample to be measured (b) a design-side data generation step for generating design-side data based on the design pattern data (c) the measurement pattern data Step of comparing design-side data (d) Step of determining necessity of repetitive inspection based on the comparison (e) Step of instructing repetitive inspection of a specific area specified in advance based on the result of the determination