JP2000019121A - Pattern inspection apparatus, pattern inspection method, recording medium recording pattern inspection program, and recording medium recording pattern inspection data - Google Patents

Abstract

(57) [Problem] To provide a pattern inspection apparatus in which a macro has no false detection of a pseudo defect and a micro has a high defect detection accuracy. Kind Code: A1 Detection pattern data S from a sample 1 to be measured.
Observation data generator for generating ₂₂ (6,4,2,5,7,
₁₄ , ₂₁ ), a first storage device 55 for storing the detected pattern data S22, reference data generators 13, 19 for generating reference data serving as inspection standards, and a second storage device for storing the reference data. The storage device 56 and the first storage device 5
Receiving an output of 5 to detect the presence or absence of the contact hole pattern in the detected pattern data S _22, to store the contact hole inspection and survey means 16 to test the amount and size, the ideal light intensity values and dimension value A third storage device 57,
A comparison circuit 11 is provided for inputting the outputs of the first and second storage devices 55 and 56 and the output of the contact hole inspection / investigation means 16.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique for inspecting a pattern for defects, and more particularly to a two-dimensional pattern provided on a photomask pattern used when manufacturing a large-scale integrated circuit (LSI) or the like. The present invention relates to a pattern inspection apparatus, a pattern inspection method, a recording medium on which a program for executing the inspection method is recorded, and a recording medium on which data having a specific structure used for executing the inspection method is recorded.

[0002]

2. Description of the Related Art One of the causes of a decrease in LSI manufacturing yield is a mask pattern generated on a photomask (or reticle) used when drawing a fine LSI pattern on a semiconductor wafer by photolithography. Defects. Recently, as the integration density of LSI chips has increased, the minimum size of a pattern formed on a semiconductor wafer has been shifting to the sub-quarter micron to nanometer level. With the miniaturization of the minimum dimensions of patterns, pattern inspection equipment that inspects defects of patterns having such fine dimensions with high accuracy and high efficiency is required, and the development of this type of pattern inspection equipment is actively pursued. Have been done.

[0003] Conventional pattern inspection apparatuses are roughly divided into two types: (1) two measurement samples on which the same pattern is drawn are observed by different detection means, and the difference between the two is compared and detected by an appropriate defect detection algorithm. And observing the sample to be measured on which the pattern is drawn by the detecting means,
There is a method (database comparison) of comparing this with the design pattern data of the pattern using an appropriate defect detection algorithm to detect a defect. In the former case, the same defect is detected because two samples to be measured on which the same pattern is drawn are observed.
When it is present on one sample to be measured, there is a disadvantage that the defective portion cannot be detected.

In the latter case, such a problem does not occur because the comparison with the design pattern data is performed. As an apparatus for performing inspection using design pattern data, for example, a pattern inspection apparatus shown in a document (high-precision fully automatic reticle inspection apparatus for super LSI, electronic materials, September 1983, p. 47), or Japanese Patent Publication No. 140489/1989. And a pattern inspection apparatus disclosed in Japanese Patent Application Laid-Open Publication No. H10-260,086. Design pattern data used when manufacturing (drawing) the reticle,
It is desirable that the design pattern data used when performing the inspection by inputting to the pattern inspection apparatus is matched. The drawing apparatus and the pattern inspection apparatus designed and manufactured based on such an idea should be used in pairs. Thus, an efficient system can be constructed.

Incidentally, recent LSI chips employ multilayer wiring. A contact hole formed for the purpose of conducting each pattern surface composed of a plurality of layers has a pattern area smaller than a design value, or a difference in a contact hole formation position increases a resistance value between different wiring layers,
Contact holes cannot be conducted between different wiring layers.

A photomask or a reticle generally has a pattern formed of a chromium (Cr) film or the like formed on a substrate such as quartz glass. In order to form the pattern of the Cr film, the following steps are required: i) First, a substrate such as quartz glass and a C
A mask blank composed of an r film is prepared. Then, a photoresist (hereinafter simply referred to as “resist”) is applied on the mask blank and exposed using light, an electron beam, X-rays or the like; ii) Thereafter, the exposed mask blank is developed and washed ( Rin)) to create a resist mask; iii) and further, using this resist mask, selectively etch the underlying Cr film by RIE or the like; iv) Finally, remove the resist, Wash residue etc.

Through such a series of steps, a photomask and a reticle are completed. However, there are defects in the shape and position of the pattern manufactured in these series of processes,
When substantially transparent deposits are present on a substrate such as quartz glass as in the case where the resist film is left unwashed, normal exposure using a stepper or the like cannot be performed on a semiconductor wafer. As described above, the area (missize) / position shift error of the contact hole pattern and the adhesion of the transparent film are problems that largely affect the quality of the mask and the LSI manufacturing technology using the same.

[0008]

However, in the above-mentioned conventional pattern inspection apparatus, there is a risk that the contact hole may be missed in size or misplaced. That is, for example, in the former method of comparison of the sample to be measured, since the repetitive reproducibility of the pattern is used, it cannot be detected when the contact hole observed at the same time similarly has a missize or displacement.

In the latter database comparison method,
In order to avoid false defects, an algorithm is used that allows a certain amount of pattern edge misalignment between the reference database and the observed pattern. Detection is difficult unless there is a defect such as a step in the portion. Here, the “pseudo-defect” means a defect that satisfies a predetermined finish standard and is practically acceptable.

[0010] Further, in the conventional apparatus, since a detection algorithm is not so extensive as to recognize the entire contact hole, the contact hole portion is individually observed and determined as each edge or corner portion. In the case of such a local observation, even if a contact hole missize occurs, it is treated as a displacement of each edge constituting the contact hole as a result.
There is a problem to be improved such that an error in the area cannot be detected.

In order to accurately detect such a missize defect or a position shift defect of the contact hole pattern, as shown in Japanese Patent Application Laid-Open No. 7-128248, each of the contact hole pattern of the reference pattern and the pattern to be inspected is contacted. A method has been proposed in which an area is extracted and the area and position are compared. However, 1-4048
Even when the apparatus described in Japanese Patent Application Laid-Open No. 9-128904 and the technique described in Japanese Patent Application Laid-Open No. 7-128248 are combined, problems have recently become apparent with respect to recently used photomasks or reticles. One of the reasons is that the unit chip size has become larger and the area of the unit exposure region has become larger as the integration degree of the LSI increases. As described above, while the size of the substrate of the photomask or the reticle is increasing, the shape of the pattern formed on the substrate is becoming more complicated and denser, and the size thereof is becoming finer. For this reason, it is becoming increasingly difficult for recent photomasks and reticles to achieve uniform pattern finish accuracy over the entire surface of a single mask, and in actual masks, this lack of in-plane uniformity poses a problem. This is because such a situation has begun to occur.

In other words, even if a missize defect or a position shift defect in a contact hole portion can be detected with high accuracy in a certain portion of one mask, if the in-plane uniformity is insufficient, the mask is used. In the pattern of the above another portion, the pattern finished dimension and the tendency of positional deviation differ. For this reason, in the conventional database comparison type inspection apparatus, even if the inspection apparatus is adjusted so that a false defect is not erroneously detected in a certain part, the pattern in another part of the mask has a pseudo defect due to these dimensional errors. Erroneous detection occurs frequently.

The cause of the pseudo defect is as follows.
(1) A database comparison method in which a pattern to be inspected is always compared with reference data obtained from design pattern data. (2) Means for adjusting an inspection apparatus so as not to erroneously detect a pseudo defect in a certain portion includes: The method is mainly performed by finely adjusting the pattern shape on the reference data side obtained from the design pattern data so as to match the observed pattern to be observed. (3) For this reason, for a mask having insufficient in-plane uniformity. In this case, the pattern mismatch occurs in a region other than the partial region in which the inspection apparatus is previously adjusted for each inspection target mask.

As the LSI advances, the minimum size of a pattern has become smaller and smaller. As a result, the dimensions that must be detected as pattern defects are also extremely small. On the other hand, a defect such as a slight displacement, such as a mask with insufficient in-plane uniformity described above, is a defect that is practically acceptable and is a pseudo defect.
Under these circumstances, the ability to detect minute defects from a local viewpoint, and the possibility of pseudo defects even in the case of a mask with insufficient in-plane uniformity from a global viewpoint. There is a need for a pattern inspection apparatus and a pattern inspection method that have both a redundant determination capability that does not cause erroneous detection.

In view of the above problems, the present invention is to provide a pattern inspection apparatus which has redundancy on a global basis, does not detect false defects erroneously, and has high local defect detection accuracy. Aim.

Another object of the present invention is to provide a pattern inspection method in which false defects are not erroneously detected and the defect detection accuracy is high.

Still another object of the present invention is to provide a recording medium on which a pattern inspection program necessary for performing a pattern inspection having a global redundancy and a high local defect detection accuracy is recorded. It is to be.

Still another object of the present invention is to provide a recording medium on which pattern inspection data used for pattern inspection which has redundancy on a global scale and has high local defect detection accuracy is recorded. .

[0019]

In order to achieve the above object, a first feature of the present invention is that an observation data generating section for generating detection pattern data corresponding to a pattern of a sample to be measured, and storing the detection pattern data. A first storage device for performing the operation, a reference data generation unit for generating reference data serving as an inspection reference, a second storage device for storing the reference data,
A contact hole inspection / inspection means for receiving the output of the first storage device, detecting the presence or absence of a contact hole pattern in the detected pattern data, and verifying at least one of the light amount and the size; A third storage device for storing at least one of the values;
And a comparison circuit for inputting the output of the storage device described above and the output of the above-described contact hole inspection / investigation means.

The observation data generation unit according to the first aspect of the present invention includes an optical image acquisition unit that irradiates a sample to be measured with light and obtains an optical image corresponding to a pattern of the sample to be measured. The photoelectric conversion unit includes a photoelectric conversion unit that converts an electric signal into an electric signal, a sensor circuit that converts an analog electric signal obtained by the photoelectric conversion into detection pattern data including a digital electric signal, and the like. Further, the reference data generation unit includes a bit pattern generation circuit, a reference data generation circuit, and the like. The bit pattern generation circuit reads design pattern data used for drawing a pattern on a sample to be measured from a data memory such as an external storage device, develops the data for each pixel, and converts the data into binary or multivalued data. Also, the reference data generation circuit superimposes a blur function simulating an adjacent pixel interference characteristic of an observation optical system (optical image acquisition unit) or a sensor (photoelectric conversion unit) of the pattern inspection apparatus to generate reference data serving as an inspection reference. produce.

The data stored in the third storage device is classified and stored separately according to the shape and size of the contact hole, and can be read out according to this classification.
That is, the data stored in the third storage device has a predetermined number of storage areas for each classification, and when a new pattern is written, when the number exceeds a predetermined number, the old pattern is stored in a first-in first-out manner. Data can be sequentially deleted and the most recent pattern can be kept at all times. The information of the contact hole stored in the third storage device includes not only the pattern data but also the dimension of a section of the contact hole having a brightness equal to or more than a predetermined threshold, the peak value of the light amount, and the brightness of the section. Can be stored as attribute information.

The contact hole inspection / investigation means of the pattern inspection apparatus according to the first aspect of the present invention may be constituted by software using a general-purpose computer system, and may include a contact hole adjustment circuit, a contact hole detection circuit and the like. May be realized by preparing the above hardware. Here, the contact hole detection circuit detects a certain number of contact hole-like patterns that should be present in the mask under inspection using a predetermined detection algorithm. For this reason, the contact hole detection circuit reads the detection pattern data stored in the first storage device and detects the presence or absence of a contact hole pattern in the detection pattern data. The method includes: (a) a buffer having a structure capable of reading out the detection pattern data stored in the first storage device in a two-dimensional manner, and having a fixed size (within about ten and several tens pixels). In the template. Calculation of luminance data (light amount level) for each pixel is performed on this template. When observed with transmitted light, a pixel pattern in which the luminance distribution is convex from the surroundings (when the luminance distribution has a quadrangular pyramid shape) is detected; (b) a contact hole stored in the third storage device A method of performing pattern matching with a shape pattern and an appropriate algorithm; or (c) A processing circuit in which an appropriate algorithm such as detecting four corner portions of a contact hole shape on a template is installed.

On the other hand, the contact hole investigating circuit judges the correctness of the pattern shape using some candidate patterns having shapes and dimensions similar to the contact hole pattern detected by the contact hole detecting circuit and an appropriate comparison judgment algorithm. . The “several candidate patterns” are candidate patterns read from the third storage device and having shapes and dimensions similar to the contact hole-like patterns detected by the contact hole detection circuit. Then, the contact hole investigation circuit detects the area of the detected contact hole portion,
Analysis such as total size and light quantity is performed and output immediately to the comparison circuit. That is, (a) information indicating that a contact hole has been detected, that is, an identification flag,
Information such as (b) the coordinates, (c) whether the pattern is correct or not, the peak value of the light amount, and the sum of the light amounts in a certain range around the peak value, which are calculated by the contact hole inspection circuit, are output. The contact hole investigating circuit may add flag information indicating that the contact pattern is included in the detected pattern data to the corresponding pixel pattern data as attribute bits.

Some candidate patterns of the contact hole shape stored in the third storage device are obtained by first obtaining detection pattern data using an actual inspection target mask prior to the original inspection, and performing first storage. A method of extracting from patterns temporarily stored in the apparatus and holding them as candidate patterns can be adopted.

The comparison circuit of the pattern inspection apparatus according to the first aspect of the present invention includes a defect detection algorithm, a defect determination threshold value, a degree of allowable pattern edge position shift, etc., according to the output of the contact hole inspection / investigation means. Has a function that can be changed in real time. The comparison circuit can instruct whether or not to employ (reflect) the output of the contact hole inspection / investigation means for defect determination by a command from a computer having a higher concept that controls the apparatus. Specifically, in the conventional comparison circuit, in order to avoid false detection of a pseudo defect, the reference data (output from the second storage device) and the detection pattern data (output from the first storage device) are used as references. Therefore, an algorithm is adopted in which a certain amount of pattern edge position shift is permitted and adjusted. However, this is performed while the signal indicating that a contact hole is detected is active. Then, the exact displacement between the reference data and the detection pattern data is measured, and it is strictly checked whether the displacement is allowable; (b) The presence or absence of a shape abnormality from the contact hole inspection circuit and the occurrence of a bitch abnormality Take measures such as making a defect judgment based on the analysis results such as presence / absence. In this way, the comparison circuit uses the signal indicating that a contact hole has been detected, changes the threshold value only at the necessary moment, or changes the judgment algorithm while maintaining the algorithm provided in the normal comparison circuit. By doing so, a more strict pattern inspection can be performed, and a defect pattern can be pointed out using a contact hole shape abnormality signal output by the contact hole inspection / investigation means.

The second feature of the present invention is that (a) a step of observing a pattern of a sample to be measured and generate detection pattern data; (b) a step of storing the detection pattern data in a first storage device; (C) a step of generating reference data serving as an inspection standard; (d) a step of storing the reference data in a second storage device; (e) examining output data of the first storage device; Detecting the presence or absence of a contact hole pattern at
(F) measuring at least one of the light quantity and the dimension of the contact hole pattern obtained by the detecting step; (g) at least one of the light quantity and the dimension of the contact hole pattern obtained by the measuring step and the third Comparing and examining the data stored in the storage device of (1); (h) referring to the result obtained by the detecting step and the result obtained by the comparing / investigating step, the first and second storages; Comparing the output of the device to detect a defect in the pattern of the measured sample;
(I) At least one of the light amount and the dimension of the contact hole pattern obtained by the measuring step is determined by a third method.
Is a pattern inspection method that includes at least a step of storing in a storage device.

According to a second feature of the present invention, a signal indicating that the presence of a contact hole pattern has been detected is
The conventional algorithm for comparing the detection pattern data with the reference data can be used as it is, and the threshold value can be changed or the determination algorithm can be changed only at the necessary moment.
Therefore, a more strict pattern inspection can be performed.

A third feature of the present invention is a computer-readable recording medium on which a program for executing the pattern inspection method according to the second feature is recorded.
That is, a program for implementing the inspection method according to the second feature is stored in a computer-readable recording medium, and the program stored in the recording medium is read by a computer system. The inspection method according to the second feature can be realized by executing this program by the (CPU). Here, the recording medium is, for example, RAM, ROM
And other media such as a semiconductor memory, a magnetic disk, an optical disk, a magneto-optical disk, and a magnetic tape.

If the recording medium according to the third aspect of the present invention is used, the conventional algorithm for comparing the detected pattern data with the reference data remains unchanged, and the threshold value is changed only at a necessary moment, or the judgment algorithm is changed. Can be changed. Therefore, a more strict pattern inspection can be performed.

A fourth feature of the present invention is that the computer-readable recording medium records data having a specific structure necessary for executing the pattern inspection method. This data corresponds to data recorded in the third storage device of the pattern inspection apparatus according to the first feature. That is, the pattern inspection is performed by comparing the detected pattern data with the reference data in the comparison circuit. When the comparison circuit performs the comparison processing, the operation mode for controlling (or changing) the operation mode of the comparison circuit is determined. A signal (abnormal signal) is required. The recording medium according to the fourth aspect of the present invention records pattern inspection data that is read and used in the process of generating the abnormal signal. Specifically, the pattern inspection data includes: a data area classified according to the shape of the contact hole pattern; a data area classified according to the dimension of the contact hole pattern; And at least a data area classified as As described above, the pattern inspection data has a predetermined number of data areas for each classification, and stores “ideal dimension values” and “ideal light amount values”. The “ideal dimension value or light amount value” is an average value of a predetermined number of pieces, and is updated sequentially as the inspection proceeds. That is, after the operation of the predetermined contact hole investigation is completed, the pattern data of the contact hole-like pattern being handled, the light amount value, the dimension along the predetermined direction, and the like are recorded on the recording medium according to the fourth aspect of the present invention. Will be saved. If a predetermined number is exceeded when new data is written to the recording medium, the old pattern inspection data can be sequentially deleted by the first-in first-out method, and the latest pattern inspection data can be always retained. In this manner, the “recent contact hole pattern” is read out, and a defect can be detected while comparing with this. For this reason,
Even when the finish uniformity of the entire mask is insufficient,
Since the relative comparison with the pattern in the vicinity of the target pattern is performed, the influence of the non-uniformity can be avoided. In this case, since it is not an absolute comparison with the reference data, only a peculiar pattern can be pointed out as a defect.

[0031]

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

(First Embodiment) FIG. 1 is a schematic overall view of a pattern inspection apparatus according to a first embodiment of the present invention (the pattern inspection apparatus of the present invention has various configurations. It should be noted that, although possible, FIG. 1 is only an example).

As shown in FIG. 1, a pattern inspection apparatus according to a first embodiment of the present invention, observation data generator for generating a detection pattern data S ₂₂ corresponding to the pattern of the measured sample 1 (6, and 4,2,5,7,21,14), the first storage device for storing the detected pattern data S ₂₂ 5
5, the reference data generating unit that generates reference data S ₃₁ to be inspected reference (13, 19), and the second storage device 56 for storing the reference data S _31, the output of the first storage device 55 receiving, detecting the presence or absence of the contact hole pattern in the detected pattern data S _22, a contact hole inspection and survey means 16 for assaying at least one of the light intensity and size, at least one of the ideal light intensity values and dimension value It comprises at least a third storage device 57 for storing, a comparison circuit 11 for inputting the outputs of the first and second storage devices and the output of the contact hole inspection / investigation means 16.

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. A photoelectric conversion unit 7 for converting an optical image into an electric signal S ₉ , and a sensor circuit 21 for converting a photoelectrically converted analog electric signal S ₉ into detection pattern data S ₂₂ composed of a digital electric signal.
And so on.

A sample stage 2 on which a 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 3 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, known servo motors and step motors may be used. The position coordinates of the sample stage 2 are measured by, for example, a laser length measuring system, and the output is sent to a position circuit (not shown). The position coordinates output from the position circuit are fed back to the table control circuit 3.

The sample to be measured (photomask) 1 is automatically supplied to the sample table 2 by an autoloader (not shown), and is automatically discharged after the inspection. Above the sample table 2, a light irradiating unit including a light source 6 and a condenser lens 4 is arranged. Light from the light source 6 irradiates the photomask 1 via the condenser lens 4. Below the photomask 1,
A signal detection unit including a condenser lens 5 and a photoelectric conversion unit (photodiode array) 7 is arranged. And
The transmitted light transmitted through the photomask 1 is imaged and irradiated on the light receiving surface of the photoelectric conversion unit (photodiode array) 7 via the condenser lens 5. The focus of the condenser lens 5 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 7 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 7 detects the measurement signal S ₉ corresponding to the pattern to be inspected on the photomask 1. The measurement signal S ₉ is converted into digital data by the sensor circuit 21, is arranged in the line buffer 14, and is input to the first storage device 55 as detection pattern data S ₂₂ . The output of the first storage device 55 is sent to the comparison circuit 11 via the contact hole detection / investigation means 16 or directly. Detection pattern data S ₂₂ is 8-bit unsigned data, for example, assumed to represent the brightness of each pixel.

This type of pattern inspection apparatus normally reads out these pattern data from the photodiode array 7 in synchronization with a clock frequency of about 10 to 30 MHz, rearranges the data appropriately, and raster-scans a two-dimensional image. Treated as data.

Further, the pattern inspection apparatus according to the first embodiment of the present invention has an input unit (not shown) for receiving an input of data and instructions from an operator, and an output unit (not shown) for outputting an inspection result. ), A data memory 12 storing design pattern data and the like, and a program memory 15 storing an inspection program and the like. The input unit 11 not shown is composed of a keyboard, a mouse, a light pen, a floppy disk device, or the like. The output unit is configured by a display device, a printer device, or the like.

The reference data generator of the pattern inspection apparatus according to the first embodiment of the present invention comprises a bit pattern generator 13, a reference data generator 19, and the like. The bit pattern generation circuit 13 and the reference data generation circuit 19 are connected to an external storage device via a data bus of the host computer 10. The data memory 12 and the program memory 15 as external storage devices 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 are included.
The design pattern data in the data memory 12 is stored by dividing the entire inspection area into strip-shaped areas. This strip-shaped design pattern data is stored in the CPU of the host computer.
10 and sequentially transferred to the bit pattern generation circuit 13. The design pattern image data S ₃₀ generated by the bit pattern generation circuit 13 is
In creating a reference data S ₃₁ that superimposes to the inspection standard blurred function was like simulating the adjacent pixels interference characteristics of the observation optical system and sensor of the pattern inspection device, is temporarily stored in the second storage device 56. Reference data S ₃₁ output from the second storage device 56 is sent to the comparator circuit 11, reference is compared by a suitable comparison algorithm and output measurement signal (detection pattern data S ₂₂₎ from the first storage device 55 If it is different from the data (design pattern data), it is determined to be a defect. At the time of comparison by the comparison circuit 11, an output signal from the contact hole inspection / investigation means 16 is also used.

FIG. 2 shows the first storage device 5 shown in FIG.
5 is a schematic diagram showing details of the contact hole inspection / investigation means 16 and the periphery thereof. The contact hole inspection / investigation means 16 of the pattern inspection apparatus according to the first embodiment of the present invention includes a contact hole adjustment circuit 50 and a contact hole detection circuit 51. Contact hole survey circuit 50, the light quantity detection circuit 52 for determining the amount of light transmitted through the contact hole pattern portion size detection circuit 53, the detected pattern data S ₂₂ for measuring the rectangular dimensions of the contact hole pattern, and the buffer 1
The detection pattern data S ₂₂ flowing through the first storage device 55 during the detection inspection can be processed in real time. The contact hole detection circuit 51, the light quantity verification circuit 52, and the dimension verification circuit 53 are connected to the third storage device 57 via the data bus 122, respectively.
The third storage device 57, the light quantity verification circuit 52, and the dimension verification circuit 53 are each composed of a data bus 123 and a buffer 156.
Is connected to the first storage device 55 via the. The second storage device 56 and the comparison circuit 11 are connected to each other via a data bus 125. The contact hole detection circuit 51 and the light amount verification circuit 52 are connected to each other, and the contact hole detection circuit 51 and the size verification circuit 53 are connected to each other via wirings 131 and 132. The contact hole detection circuit 51 is connected to the comparison circuit 11 via wirings 141, 151, and a buffer 158. Light intensity test circuit 52
Are transmitted through the wirings 142, 152 and the buffer 158, and the dimension verification circuit 53
8 is connected to the comparison circuit 11.

Note that the contact hole inspection / investigation means 16 according to the first embodiment of the present invention does not necessarily need to be constituted by hardware 50 and 51 as shown in FIG. That is, the contact hole inspection / investigation means 16
It should be noted that the functions can be realized by software using a general-purpose computer system and have functions equivalent to the following functions.

The first storage device 55 shown in FIG. 2 is output from the sensor circuit 14 temporarily holds the detected pattern data S ₂₂ aligned in each scan cycle. Contact hole adjustment circuit 50 and contact hole detection circuit 5
From 1 through the buffer 156 can be read two-dimensionally, has a detection pattern data S ₂₂ from the first storage device 55 to always read put out configure. Third storage device 5
7 can be read from the contact hole investigation circuit 50 and the contact hole detection circuit 51 at any time.

The contact hole detecting circuit 51 detects some contact hole-like patterns which should be present in the mask under inspection. For this detection, a detection algorithm described below is used.

First, as shown in FIG.
A template of 5 × 5 pixels composed of 25 two-dimensional matrix pixels is prepared. It scans the detected pattern data S ₂₂ read from the first storage device 56 at this 5 × 5 pixels templates. The brightness of the center pixel c3 and the inner ring pixels (b2 to b4, c2, c4, d2 to
d4) The brightness average value and the outer ring pixels (a1 to a
5, b1, b5, c1, c5, d1, d5, e1-e
5), and these relationships are determined as shown in FIG. 3B. (Average value of outer wheel) <(Average value of inner wheel) <(Sensor value) (1) ) Is a candidate for the desired contact hole pattern. Here, “5 × 5 pixels” means that, for example, the size of a sensor (photodiode array) per pixel is 0.2.
In the case of μm square, it is assumed that the contact hole pattern to be detected is about 1 μm square. Further, when the size of the contact hole to be detected is larger than the size of one pixel of the photodiode array 7, the template is set to (ten and several pixels) × (ten and several pixels).
What is necessary is just to make it large within. That is, following the inner ring and the outer ring (first outer ring) shown in FIG. 3A, the measurement is further performed on the outer rings of the second, third,... You just need to set up a template to calculate up to.

The contact hole detection circuit 51 can detect a contact hole pattern based on the above principle. However, the contact hole detection circuit 51 according to the first embodiment of the present invention further includes a third storage device 57.
The accuracy of the contact hole shape detection can be improved as compared with the similar calculation result for the “contact hole shape pattern to be used as an example” stored in the above. That is, the calculation result of (sensor value) − (average value of the inner ring) of the pattern extracted from the first storage device 55 and the calculation result of the “contact hole-like pattern to be used as an example” extracted from the third storage device 57 The calculation results of (sensor value) − (average value of inner ring) are almost equal, and (average value of inner ring) − (average value of outer ring) of the pattern extracted from the first storage device and the third storage device 57 It is determined whether (average value of the inner ring) − (average value of the outer ring) of the “contact hole-like pattern to be used as an example” extracted from the above is substantially the same. When the contact hole pattern is detected by such an algorithm, the contact hole detection circuit 51 sends a signal to the light quantity detection circuit 52 and the dimension verification circuit 53 to the effect that the contact hole pattern has been detected. With this algorithm, even when several types of contact hole patterns are used in one mask, it can be redundantly detected.

The dimension verification circuit 53 stores the first storage device 5 in the pixel section notified by the contact hole detection circuit 51.
The dimension of the contact hole pattern taken out from No. 5 having a light amount equal to or larger than a predetermined threshold is measured. That is, A shown in FIG.
-A change in the light amount along the A direction and a change in the light amount along the BB direction are measured. Quantity detection pattern data S ₂₂ is not measured only units of pixels. Therefore,
If the size of the contact hole-shaped pattern does not become an integral multiple of one pixel of the photodiode array 7 and the light amount changes within one pixel, the light amount value is obtained by interpolation. . Then, it is determined which of several contact hole shapes stored in the third storage device 57 is closest to.

The dimension verification circuit 53 further includes a dimension along a predetermined direction of the contact hole pattern portion being handled and a dimension value obtained from the corresponding contact hole pattern stored in the third storage device 57. (Ideal dimension value). "Ideal dimensions"
Is a dimension value that is sequentially updated as the inspection proceeds, as described later. That is, the “ideal dimension value” is determined by an average value of a predetermined number given from the latest measurement in a series of measurements accompanying the progress of the inspection. The dimension verification circuit 53 has a function of determining whether or not the error of the dimension is within a specified value and how much the size is out of the specified value, and outputting the information to the comparison circuit 11 via the buffer 158. Further, if the error is equal to or greater than the predetermined value, it is determined that an error has occurred, and the comparison circuit 11 is notified through the signal lines 143 and 153.

The light quantity verification circuit 52 detects the detection pattern data S
The sum of the light amounts of the contact hole pattern portions ₂₂ is calculated and compared with the ideal light amount value stored in the third storage device. The “ideal light amount value” is an average value of a predetermined number of recent times, and is sequentially updated as the inspection proceeds. The light quantity verification circuit 52 has a function of determining whether or not the error of the light quantity is within a specified value, and how much the light quantity deviates from the specified value, and outputs information to the comparison circuit 11 via the buffer 158. Further, if the error is equal to or more than the specified value, it is determined that an error has occurred, and the comparison circuit 11 supplies the signal line 142,
Notify through 152.

The reason why some contact hole-like patterns are stored in the third storage device 57 is because it is assumed that several types of contact holes are used in one mask. May be one way.

When the operation of the contact hole inspection circuit 50 is completed, the pattern data of the contact hole pattern being handled, the light amount value calculated by the light amount verification circuit 52, and the predetermined direction calculated by the size verification circuit 53 are obtained. The dimensions and the like are stored in the third storage device 57. The data recorded in the third storage device 57 is classified and arranged in a data area provided with an identification number for each contact hole shape as shown in FIG. That is, the pattern data (x, y, d) of the contact hole pattern
x, dy) and the light amount value are stored in the data area of the corresponding classification of the contact hole pattern. At this time, if the amount of data exceeds a predetermined storage number, the oldest data is deleted.

The comparison circuit 11 used in the pattern inspection apparatus according to the first embodiment of the present invention employs the same defect detection algorithm as the prior art as a basic technology. This “defect detection algorithm” is used to detect the detected pattern data and the reference data efficiently without erroneously detecting a pseudo defect.
₂₂ is an algorithm that allows a certain degree of positional deviation of the reference data S _31. However, the first embodiment of the present invention differs from the prior art in that during the period in which the signal indicating that the contact hole is being detected from the contact hole detection circuit 51 is present, the operation of allowing the displacement to some extent is stopped. can so closely to measure the positional deviation of the reference data S ₃₁ and the detected pattern data S _22.

Further, under the condition for pointing out a defect, the light quantity verification circuit 5 of the contact hole inspection circuit 50 described above is used.
2 and the error signal output from the dimension verification circuit 53 can also be taken into account. As described above, by taking into account the error signals output from the light quantity verification circuit 52 and the dimension verification circuit 53, for example, when a translucent film is attached to the contact hole and the transmitted light quantity of the detection pattern data is reduced, It is possible to point out a defect in the contact hole portion that could not be detected by the algorithm of the above.

As described above, changing the conventional “defect detection algorithm” to operate the comparison circuit 11 is as shown in FIG.
As shown in (1), this can be realized by providing signal lines 141 and 151 for notifying the comparison circuit 11 directly from the contact hole detection circuit 51. The signal to provide to the comparator circuit 11 in synchronism with the original detection pattern data S _22, and outputs via the delay means (buffer) 158 suitable delay.

The processing after the defect detection by the comparison circuit 11 is the same as that of the conventional pattern inspection apparatus. The coordinates at which the defect exists, the detected pattern data S ₂₂ , and the reference data S ₃₁ are read into the CPU 10 of the host computer, and the data is stored in the data memory. 12
Or output to a screen of an output device.

In the above description, some candidate patterns of the contact hole shape built in the third storage means 57 have been described as being already stored. However, actually, the detection pattern data can be acquired and stored by using the actual inspection target mask in the following procedure.

(A) The coordinates of a contact hole pattern portion to be a sample of a mask to be inspected are designated. And
The coordinates given contact hole pattern portions actually examined, in the first storage device 55, and stores the corresponding detection pattern data S ₂₂ temporarily; (b) a first embodiment of the present invention The storage data of the first storage device 55 is read out to the CPU 10 of the host computer that controls the pattern inspection apparatus according to (1). (C) A pattern portion that is a candidate is extracted from the read pattern and written into the third storage device 57; D) The above is repeated when the candidate pattern has several sizes and shapes.

FIG. 2 shows a bus for reading data stored in the first storage device 55 to the CPU 10 of the host computer, and a bus from the CPU 10 of the host computer to the third storage device 5.
7 are not shown (the paths of these buses are shown by solid lines in FIG. 1).

As described above, according to the first embodiment of the present invention, generally (in a macro), a mask in which the finished uniformity of the entire mask is insufficient with only the conventional comparison circuit is inspected. In this case, it is possible to avoid an allowable pattern error, that is, a phenomenon in which a pseudo defect is erroneously pointed out. Moreover, according to the first embodiment of the present invention, it is possible to point out a local (micro) displacement error of the contact hole pattern. The principle is that the pattern error of the contact hole is investigated by the contact hole surveys circuit 50, positional deviation of the detected pattern data S ₂₂ and the reference data S ₃₁ is to carry out a rigorous comparison in the comparison circuit 11.

As described above, the contact hole investigating circuit 50 according to the first embodiment of the present invention always reads the “recent contact hole pattern” held in the third storage device 57 and compares it with the read data. While detecting defects. Therefore, even when the finished uniformity of the entire surface of the mask is insufficient, the relative comparison with the pattern in the vicinity of the target pattern is performed, so that the influence of the non-uniformity can be avoided. In this case, since it is not an absolute comparison with the reference data, only a peculiar pattern can be pointed out as a defect.

The detection pattern data S ₂₂ in the comparison circuit 11
See operation to allow a degree of misalignment between the data S ₃₁ A, except in the contact hole pattern is useful to reduce the erroneous detection of the false defects. However, this algorithm cannot point out the positional deviation of the contact hole pattern. Therefore, an algorithm that stops the operation of permitting the displacement only during the detection of the contact hole pattern as in the first embodiment of the present invention is effective.

A program for implementing the inspection method according to the first embodiment of the present invention is stored in a computer-readable recording medium, and the program stored in the recording medium is executed by a host computer system. The data may be read into the memory 15. Then, the program of the inspection method according to the first embodiment of the present invention stored in the program memory 15 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 RAM,
Semiconductor memory such as ROM, magnetic disk, optical disk,
A medium such as a magneto-optical disk or a magnetic tape on which a program can be recorded.

Modification Example 1 of First Embodiment In the conventional pattern inspection apparatus, the positional error of the contact hole pattern as shown in FIG. 4D is also a defect for which defect detection is difficult. Therefore, figure detection pattern data S ₂₂ as a modification of the first embodiment (Modification 1) 4
A description will be given of a defect detection method in the case where a positional shift as shown in FIG.

As shown in FIG. 6, the contact hole inspection circuit 50 according to the first modification is different from the light amount inspection circuit 5 shown in FIG.
2 and a dimension verification circuit 53 in addition to a pitch verification circuit 5
Equipped with four. The pitch test circuit 54 detects an error in the arrangement pitch of the contact hole pattern, and if the error is equal to or greater than a specified value, determines that the error is an error and notifies the comparison circuit 11 via the signal lines 144 and 154.

Using FIG. 6 and FIG.
Operation 4 will be described.

(I) First, similarly to the dimension verification circuit 53,
Recognizing a predetermined section of the detection pattern in the data S ₂₂ taken out from the first storage device 55 in a pixel section from the contact hole detection circuit 51 of the notification. The “predetermined section” is a section in which the amount of light is equal to or greater than a predetermined threshold.

(Ii) Next, the center coordinate calculation circuit 59 shown in FIG. 7 calculates the x, y center coordinates of the contact hole pattern. The method of obtaining the center in the center coordinate calculation circuit 59 is similar to the size verification circuit 53, in which the size of a pixel section that is equal to or larger than a predetermined threshold is obtained for each of the X and Y directions.
What is necessary is just to obtain each center coordinate. Alternatively, the center coordinates can also be obtained by using a method of calculating the product sum of the brightness of each pixel and the coordinate position, calculating the total light amount and calculating the center of gravity.

(Iii) The center coordinates thus obtained are stored in one of the coordinate registers 60. The coordinate register 60 stores the center coordinates of the contact holes detected sequentially. The contact hole configuration estimating circuit 61 reads each coordinate of the coordinate register 60, estimates and calculates the pitch of the contact hole, and determines whether each coordinate stored in the coordinate register 60 becomes a matrix. In general, the contact holes rarely exist (are arranged) alone, and in most cases, a certain number of contact holes are arranged collectively at regular intervals. The step of estimating and calculating the pitch according to the first modification utilizes the characteristics of the arrangement of the contact holes. Specifically, (a) the contact hole configuration estimation circuit 61 reads the first and second center coordinate data from the coordinate register 60,
It is determined whether the X coordinate or the Y coordinate is the same. (B) Further, the coordinate pitch is calculated; (c) Then, the third center coordinate data is read out, and the first and second center coordinates are read. Check if there is the same X coordinate or Y coordinate as any of the data. (D) Further, calculate the pitch with the first and second center coordinate data, and calculate the "pitch between the coordinates" calculated earlier.
Test whether the pitch is the same as one of the above.

(Iv) By performing the above test, it is estimated how each coordinate has an adjacent relation. Then, a certain “coordinate group arranged collectively” can be estimated. Then, when the next “coordinate group that is arranged collectively”, which is different from the “coordinate group that is arranged collectively”, is approached, each coordinate of the “coordinate group that is arranged collectively” that has been arranged earlier is pitch error. A sending error determination is made to the calculation circuit 62.

(V) The pitch error calculating circuit 62 judges the variation of the cycle of each coordinate data notified from the contact hole configuration estimating circuit 61, and indicates an error which is larger than an allowable value by an error signal _S64 . . Error signal S ₆₄
Is notified to the comparison circuit 11 through the signal lines 144 and 154 and the buffer 158.

(Vi) In the comparison circuit 11, when the defect of the contact hole portion notified of the pitch error is determined, the conventional correction for allowing a fine positional deviation is stopped and a strict positional deviation is inspected. Operation mode is changed. Then, it is possible to remarkably point out the edge shift of the contact hole portion, and it is possible to detect an error in the contact hole.

According to the first modification, in addition to the case where the hole size of the contact hole itself is normal but the position is shifted as shown in FIG. 4D, the periodic direction (continuous arrangement) as shown in FIG. The mis-size of the contact hole (direction, x direction) is also detected as a deviation of the center coordinates of the contact hole. For this reason, the missize is also detected as a displacement, but it is still a defect, so there is no practical problem.

Since the coordinate data stored in the coordinate register 60 is used as it is, the used data is accumulated as it is. The coordinates notified by the pitch error calculation circuit 62 to the comparison circuit 11 through the buffer 158; It is erased under any of the following conditions;

Modification 2 of First Embodiment Contact hole investigation circuit 50 shown in FIGS. 2 and 6
Is output to the comparison circuit 11 via the buffer 158. The buffer 158 is set an appropriate delay to synchronize the timing of the original detection pattern data S ₂₂ is inputted reference data S ₃₁ and timing to be input to the comparison circuit 11. As shown in FIG. 9 in place of the buffer 158, the original observed data (detection pattern data S ₂₂₎ d ₇ ~d ₀ in the attribute bits d _8, d _9,
there is a method of adding d _10, d _11.

That is, the original 8 for each pixel of the observation data
In addition to the bit data d _{7 to} d ₀ , the 4-bit data d ₈ ,
The additional information of d ₉ , d ₁₀ , and d ₁₁ is superimposed. Bit data d ₈ becomes “1” when a contact hole is detected,
Other bits are "0". Bit data d
₉ , d ₁₀ , and d ₁₁ are bits that are “1” when an abnormality is detected by the light amount inspection circuit 52, the dimension inspection circuit 53, and the pitch inspection circuit 54, respectively, and are “0” when they are normal. Then have standing d ₈ bits shown in FIG. 9, if still any bit of d ₉ to d ₁₁ is stood, the contact hole surveys circuit 50 in the contact hole pattern including the pixel of the detected pattern data This indicates that an error has been detected. This error attribute information may stand for not only one pixel but also several pixels in the contact hole pattern.

FIG. 10 is a schematic diagram showing details of the first storage device 55, the contact hole investigation circuit 50, and the vicinity thereof according to Modification 2 of the first embodiment of the present invention. As shown in FIG. 10 in place of the buffer 158 shown in FIGS. 2 and 6, the attribute bits d ₈ to the original observed data d ₇ to d ₀ as shown in FIG. 9 with a buffer 60, d _9, d
Are added to _10, d _11. Buffer 60 shown in FIG. 10 has the function of adjusting the synchronization of the detection pattern data S ₂₂ composed of signal output and the detected pattern data d ₇ to d ₀ of the contact hole survey circuit 50. The comparison circuit 11 calculates the original observation data d _{7 to} d ₀ and the attribute bits d ₈ , d ₉ , d
_10, for consideration of the signal d ₁₁ to defect determination.

[0077] In the description in (Second Embodiment) In the first embodiment, it detects the pattern data S ₂₂ in the third storage device 57 is stored as a sample, or the detection pattern data S It is assumed that data that is very similar to ₂₂ is stored. Further, each circuit 52, 53, (54) of the contact hole investigation circuit 50
Based on the light quantity assay detected pattern data S _22, the dimensions assay or was further subjected to pitch assay. Second embodiment of the present invention
In the embodiment using the reference data S ₃₁ read from the second storage device 56 to these determinations.

FIG. 11 is a schematic overall view of a pattern inspection apparatus according to a second embodiment of the present invention. As shown in FIG. 11, the second pattern inspection apparatus according to the embodiment of the observed data generation unit for generating a detection pattern data S ₂₂ corresponding to the pattern of the measured sample 1 of the present invention (6,4,2 , and 5,7,21,14), a first memory device 55 for storing the detected pattern data S _22, the reference data generating unit that generates reference data S ₃₁ to be inspected reference (13, 19), second storing this reference data S ₃₁
Receiving the output of the storage device 56 and the output of the first storage device 55,
To detect the presence or absence of a contact hole pattern in the detected pattern data S _22, to store the contact hole inspection and survey means 16 for assaying at least one of the light intensity and size, at least one of the ideal light intensity values and dimension value It comprises at least a third storage device 57 and a comparison circuit 11 for inputting the outputs of the first and second storage devices and the output of the contact hole inspection / investigation means 16.

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. A photoelectric conversion unit 7 for converting an optical image into an electric signal S ₉ , and a sensor circuit 21 for converting a photoelectrically converted analog electric signal S ₉ into detection pattern data S ₂₂ composed of a digital electric signal.
And so on.

The sample stage 2 on which the photomask 1 as the sample to be measured is mounted is moved or rotated in a predetermined direction such as the X direction or the Y direction by the table control circuit 3 connected to the host computer (CPU) 10. it can. Above the sample table 2, a light irradiating unit including a light source 6 and a condenser lens 4 is arranged. Below the photomask 1, a signal detection unit including a condenser lens 5 and a photoelectric conversion unit (photodiode array) 7 is arranged. The photodiode array 7 as a photoelectric conversion unit is a line sensor or an area sensor provided with a plurality of optical sensors. The photodiode array 7 is connected to the sensor circuit 21,
Are connected to the line buffer 14. The line buffer 14 is connected to the first storage device 55, and the first storage device 55 is connected to the comparison circuit 11 via the contact hole detection / investigation means 16 and via a direct path.
The contact hole detection / investigation means 16 is connected to the second storage device 56 and the third storage device 57.

Further, the pattern inspection apparatus according to the second embodiment of the present invention has an input unit (not shown) for receiving input of data and instructions from an operator, and an output unit (not shown) for outputting inspection results. ), A data memory 12 storing design pattern data and the like, and a program memory 15 storing an inspection program and the like. The data memory 12 and the program memory 15 as external storage devices 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 output side of the bit pattern generation circuit 13 connected to the CPU 10 of the host computer via a bus is connected to the reference data generation circuit 19. Reference data generating circuit 19 is a circuit to produce a reference data S ₃₁ that superimposes to the inspection standard observation optical system and blurring function was like simulating the adjacent pixels interference characteristics of the sensor pattern inspection apparatus. The reference data generation circuit 19 is connected to the second storage device 56, and the second storage device 56 is connected to the comparison circuit 11 and the contact hole detection / investigation means 16.

FIG. 12 is a schematic diagram showing the details of the first storage device 55 and the contact hole inspection / investigation means 16 shown in FIG. 11 and the periphery thereof. The contact hole inspection / investigation means 16 of the pattern inspection apparatus according to the second embodiment of the present invention includes a contact hole adjustment circuit 50 and a contact hole detection circuit 51.
The contact hole inspection circuit 50 includes a dimension verification circuit 53 for measuring a rectangular dimension of the contact hole pattern, a light intensity verification circuit 52 for determining the amount of transmitted light in the contact hole pattern portion of the detection pattern data, and the buffer 15.
8 is provided. The contact hole detection circuit 51, the light quantity verification circuit 52, and the dimension verification circuit 53 are connected to the second storage device 56 via the data bus 126, respectively. The second storage device 56 and the comparison circuit 11 are connected to each other via a data bus 125. Then, a contact hole detection circuit 51 and a light amount verification circuit 5
2. The dimension verification circuit 53 is connected to the third storage device 57 via the data bus 122, respectively. The third storage device 57, the light quantity verification circuit 52, and the dimension verification circuit 53
Each is connected to the first storage device 55 via the data bus 123 and the buffer 156. The contact hole detection circuit 51 and the light amount verification circuit 52, and the contact hole detection circuit 51 and the size verification circuit 53
132 are connected to each other. The contact hole detection circuit 51 includes wirings 141, 151, and a buffer 15.
8 is connected to the comparison circuit 11. The light amount verification circuit 52 is connected to the comparison circuit 11 via wirings 142, 152, and a buffer 158, and the dimension verification circuit 53 is connected to the comparison circuit 11 via wirings 143, 153, and a buffer 158.

In the configuration shown in FIG. 12, the contact hole detection circuit 51 notifies the light quantity verification circuit 52 and the dimension verification circuit 53 that a contact hole has been detected. While calculating the sum of the amount of the contact hole portion of the detection pattern data S ₂₂ of the light quantity detection circuit 52 to the part that is read from the first storage device 55, the second storage device 5
The sum of the amount of the contact hole portion of the reference data S ₃₁ read from 6 calculates, determines compare them.
By doing so, the ideal light quantity obtained from the design dimensions is compared with the actual observed light quantity, so that it is possible to more strictly determine whether the device is manufactured according to the design pattern.

[0085] The size detection circuit 53 also measures the dimensions of the section there is a pre-determined threshold value or more light intensity had the detected pattern data S ₂₂ first the contact hole portion reads from the storage device 55 of the part to one, the dimensions of the section there is a pre-determined threshold or the amount of light had of the contact hole portion of the reference data S ₃₁ read from the second storage device 56 is measured to determine compare them.
In this way, the theoretical pattern size obtained from the design pattern data is compared with the size of the actual observation pattern, so that it is possible to more strictly determine whether or not the product is manufactured according to the design pattern data. .

Modification 1 of Second Embodiment FIG. 13 is a schematic diagram showing details of a contact hole inspection / investigation unit 16 according to a modification (Modification 1) of the second embodiment of the present invention. is there. The contact hole inspection / investigation means 16 according to the second embodiment of the present invention is
2 does not need to be constituted by the hardware 51, 52, 53 as shown in FIG. In other words, the contact hole inspection / investigation means 16 can be realized by software using a computer system such as a general-purpose microcomputer, and can have a function equivalent to the above.

As shown in FIG. 13, the contact hole inspection / investigation means 16 according to the first modification of the second embodiment includes:
Via a microcomputer bus 79, an interface (I / F) 71 to a host computer (CPU), a RAM 72, a program memory 73, a CPU 74 of a microcomputer,
An interface (I / F) 75 to the second storage device,
An interface (I / F) 76 to the comparison circuit, an interface (I / F) 76 to the third storage device 57, and an interface (I / F) 78 to the first storage device are connected to each other. And a host computer (CPU)
10, the second storage device 56, the comparison circuit 11, the first storage device 55, and the third storage device 57 are connected via interfaces (I / F) 71, 75, 76, 77, 78, respectively. ing. The third storage device 57 may be provided inside the contact hole inspection / investigation means 16.

[0088] The program memory 73 is, the second storage device 56 reads the reference data S ₃₁ from the process; the contact of the contact calculation of the light amount of the sum of the hole portion, and reference data S _31; contact hole detection processing comparison determination processing with the sum of the amount of the hole portion; measurement of dimensions, predetermined interval, and comparison processing for determining whether the size of the contact hole portion of the reference data S _31, second embodiment of the aforementioned invention of equal The program of the predetermined processing of the form is stored. Then, a predetermined program recorded in the program memory 73 is executed according to a command from the host computer, and a function equivalent to the hardware configuration shown in FIG. 12 is realized.

A predetermined program for operating the contact hole inspection / investigation means 16 shown in FIG. 13 is stored in a computer-readable recording medium, and the program stored in the recording medium is read into a program memory 73. You may. Then, the program stored in the program memory 73 may be executed by the CPU of the microcomputer. Here, the recording medium is, for example, RA
A medium such as a semiconductor memory such as an M or ROM, a magnetic disk, an optical disk, a magneto-optical disk, a magnetic tape, or the like, on which a program can be recorded. The program memory 73 may use the same hardware as the program memory 15 shown in FIG. 15, and the recording medium may be a medium common to the program memory 15.

Modification 2 of Second Embodiment FIG. 14 shows a contact hole inspection / investigation unit 16 of a pattern inspection apparatus according to another modification (modification 2) of the second embodiment of the present invention. FIG. 2 is a schematic diagram showing one storage device 55 and its periphery.

As shown in FIG. 14, the contact hole inspecting / investigating means 16 according to the second modification includes a contact hole adjusting circuit 50 and a contact hole detecting circuit 51. The contact hole investigating circuit 50 also determines a dimension verification circuit 53 for measuring the rectangular dimension of the contact hole pattern, a light amount verification circuit 52 for obtaining the amount of light transmitted through the contact hole pattern portion of the detection pattern data, and a pitch error of the contact hole. A pitch test circuit 54 and a buffer 158 are provided.

The pitch test circuit 54 operates similarly to the first and second modifications of the first embodiment. That is, the contact hole detection circuit 51 is connected to the second storage device 5
A contact hole located notifies the pitch detection circuit 54 on the basis of the reference data S ₃₁ read from 6, reference data S
Calculate the ideal pitch based on ₃₁ . On the other hand, we obtain the actual pitch based on the first read from the storage device 55 detected pattern data S _22, determines compare them.
In this way, it will be able to determine whether or not the detected pattern data S ₂₂ present in the ideal pitch as obtained from the reference data S _31, more determination of whether can be manufactured as designed pattern data You can do it strictly.

(Other Embodiments) As described above, the present invention has been described with reference to the first and second embodiments. However, the description and drawings constituting a part of this disclosure limit the present invention. It should not be understood that there is. From this disclosure, various alternative embodiments, examples, and operation techniques will be apparent to those skilled in the art.

For example, as described in the second embodiment,
A method of using the reference data S ₃₁ read from the second storage device 56, the determination result of the contact hole survey circuit 50 described in the second modification of the first embodiment, the original detected using buffer 160 It is also possible to configure by combining a method of adding attribute bits d ₈ , d ₉ , d ₁₀ , and d ₁₀ to the pattern data d _n -d _o .

As described above, it should be understood that the present invention includes various embodiments and the like not described herein. Therefore, the present invention is limited only by the matters specifying the invention described in the claims that are reasonable from this disclosure.

[0096]

As described in detail above, according to the present invention,
It becomes possible to detect a transmissivity defect defect in the form of a semi-transparent film in a contact hole portion and a defect of a missize, which were conventionally difficult to detect.

Therefore, according to the present invention, it is possible to provide a pattern inspection apparatus having high defect detection accuracy.

According to the present invention, it is possible to provide a pattern inspection method with high defect detection accuracy.

Further, according to the present invention, it is possible to provide a recording medium on which a pattern inspection program necessary for performing a pattern inspection with high defect detection accuracy is recorded.

Further, according to the present invention, it is possible to provide a recording medium on which pattern inspection data used for pattern inspection with high defect detection accuracy is recorded.

[Brief description of the drawings]

FIG. 1 is a schematic overall view schematically showing a pattern inspection apparatus according to a first embodiment of the present invention.

FIG. 2 is a block diagram showing details of a contact hole inspection / investigation unit of FIG. 1 and a peripheral circuit thereof.

FIG. 3A is a diagram illustrating an example of a contact hole detection template, and FIG. 3B is a graph illustrating a result obtained by calculating an average brightness value using the template.

FIG. 4 is a conceptual diagram showing types of contact hole errors.

FIG. 5 is a schematic diagram showing a structure of data stored in a third storage device.

FIG. 6 is a block diagram showing details of a contact hole inspection / investigation unit of a pattern inspection apparatus and a peripheral circuit thereof according to a first modification of the first embodiment of the present invention.

FIG. 7 is a block diagram showing the inside of a pitch test circuit shown in FIG. 6;

FIG. 8 is a conceptual diagram illustrating a pitch error in a continuous arrangement direction.

FIG. 9 is a diagram illustrating a method of adding 4-bit attribute bits to bits indicating 8-bit original observation data (detection pattern data).

FIG. 10 is a block diagram showing details of a contact hole inspection / investigation unit of a pattern inspection apparatus according to Modification 2 of the first embodiment of the present invention and peripheral circuits thereof.

FIG. 11 is a schematic overall view schematically showing a pattern inspection apparatus according to a second embodiment of the present invention.

12 is a block diagram showing details of a contact hole inspection / investigation unit of FIG. 11 and a peripheral circuit thereof.

FIG. 13 is a block diagram showing a structure in a case where a contact hole detection / investigation unit is realized by software using a general-purpose microprocessor according to a first modification of the second embodiment of the present invention.

FIG. 14 is a block diagram showing details of a contact hole inspection / investigation unit of a pattern inspection apparatus and a peripheral circuit thereof according to a second modification of the second embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Photomask (sample to be measured) 2 Sample table 3 Table control circuit 4,5 Condensing lens 6 Light source 7 Photodiode array 10 Host computer 11 Comparison circuit 12 Data memory 13 Bit pattern generation circuit 14 Line buffer 15 Program memory 16 Contact hole Detecting and investigating means 19 Reference data generating circuit 21 Sensor circuit 50 Contact hole investigating circuit 51 Contact hole detecting circuit 54 Pitch verification circuit 55 First storage device 56 Second storage device 57 Third storage device 59 Center coordinate calculation circuit 60 Coordinate register 61 Contact hole configuration estimating circuit 62 Pitch error calculation circuit 71 Host CPU interface 72 RAM 73 Program memory 74 Microcomputer CPU 75 Second storage device interface 76 Comparison circuit Interface 77 First storage device interface 78 Third storage device interface 79 Microcomputer bus 121-126 Data bus 131, 132, 141-144, 151-154 Wiring 156, 157, 158, 160 Buffer

Claims (4)

[Claims] 1. An observation data generation unit that generates detection pattern data corresponding to a pattern of a sample to be measured, a first storage device that stores the detection pattern data, and reference data that generates reference data serving as an inspection standard A generation unit, a second storage device for storing the reference data, and receiving an output of the first storage device, detecting the presence or absence of a contact hole pattern in the detected pattern data, and detecting at least one of the light amount and the size. A third storage device for storing at least one of an ideal light amount value and a dimension value; an output of the first and second storage devices; A pattern inspection apparatus comprising: a comparison circuit for inputting an output of the investigation means. 2. A pattern inspection method having at least the following steps. (A) Step of observing the pattern of the sample to be measured and generating detection pattern data (B) Storing the detection pattern data in a first storage device (C) Generating reference data serving as an inspection standard (C) D) a step of storing the reference data in a second storage device; and (e) a step of examining output data of the first storage device and detecting the presence or absence of a contact hole pattern in the detection pattern data. F) measuring at least one of the light quantity and the dimension of the contact hole pattern obtained by the detecting step; and (g) measuring at least one of the light quantity and the dimension of the contact hole pattern obtained by the measuring step. 3
Comparing and examining the data stored in the storage device of (h) with reference to the result obtained in the detecting step and the result obtained in the comparing and investigating step, referring to the first and second Comparing the output of the storage device and detecting a defect in the pattern of the sample to be measured (i) determining at least one of the light quantity and the dimension of the contact hole pattern obtained by the measuring step;
Storing in the third storage device 3. A recording medium on which a pattern inspection program having at least the following steps is recorded. (A) Step of observing the pattern of the sample to be measured and generating detection pattern data (B) Storing the detection pattern data in a first storage device (C) Generating reference data serving as an inspection standard (C) D) a step of storing the reference data in a second storage device; and (e) a step of examining output data of the first storage device and detecting the presence or absence of a contact hole pattern in the detection pattern data. F) measuring at least one of the light quantity and the dimension of the contact hole pattern obtained by the detecting step; and (g) measuring at least one of the light quantity and the dimension of the contact hole pattern obtained by the measuring step. 3
Comparing and examining the data stored in the storage device in (h), referring to the result obtained in the detecting step and the result obtained in the comparing and examining step, referring to the first and second data. Comparing the output of the storage device and detecting a defect in the pattern of the sample to be measured. (Re) At least one of the light quantity and the size of the contact hole pattern obtained by the measuring step
Storing in the third storage device 4. A recording device for detecting an abnormality in the light quantity and dimensions of a contact hole pattern when comparing the detected pattern data with reference data, and recording pattern inspection data used for controlling the comparison process. The medium, wherein the pattern inspection data includes a data area classified according to a shape of the contact hole pattern, a data area classified according to a dimension of the contact hole pattern, and a light amount of the contact hole pattern. A recording medium comprising at least a data area classified as: