JPS6119139A - Pattern inspecting device - Google Patents

Abstract

PURPOSE:To enable to improve the throughput capacity of the titled device by a method wherein the model pattern and a detecting pattern are compared by the defect discriminator and when there is a defect, the coordinates on the mask, wherein the defect exists, are not only memorized, but also the model and detecting patterns of the ambient image including the defect are memorized. CONSTITUTION:The detection pattern signal (a), which is the output of an image sensor, is memorized in tandem connected temporary storage buffer memories 161-16m. The signals memorized are selected by a multiplexer 15 and the selected signal is inputted in a defect detecting circuit 17 and an image memory 20, while the signal (b) from a model pattern generator is also inputted in buffer memories 191-19m in the same manner, the signals inputted are selected by a multiplexer 18 and the selected signal is inputted in the circuit 17 and the memory 20. When any defect is not detected for a constant time, a pattern selective signal C2 is outputted from the multiplexers 15 and 18 and when a defect is detected, a transmission of signal to the circuit 17 and the memory 20 is stopped, an instruction C3 is sent to a DMA controller 21 and the contents of the memory 20 are transmitted to a magnetic disc 23.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a pattern inspection device, and particularly to a pattern inspection device suitable for use in defect inspection of circuit patterns of printed circuit boards, semiconductor integrated circuit wafers, or masks for manufacturing the same. Regarding inspection equipment.

[Background of the invention]

FIG. 1 shows an example of the configuration of a conventional mask pattern inspection apparatus. A mask 2 to be inspected mounted on an X-Y stage 1 is irradiated with a light source 3, and a pattern on the mask 2 to be inspected is detected by an image sensor 4 according to the transmitted light,
After the detection signal is quantized by the A/D converter 5, it is input to the defect determiner 8. On the other hand, the model pattern generator 6 reads the pattern data from the magnetic tape 7 which records the design data at the time of manufacturing the mask to be inspected, and outputs the pattern data from the image sensor 4 in synchronization with the output from the image sensor 4. The output signal is converted into a form that can be compared with that of the image sensor 4, and the output signal is input to the defect determination device 8 in the same way as the output of the image sensor 4. The defect determiner 8 compares the above-mentioned two signals, that is, the detection pattern and the model pattern, determines the different portion as a defect, and sends the coordinates on the mask where the defect exists to the control device 9 for control. The coordinates are stored in the device 9. Defect determination methods in the defect determination device 8 include a method of directly superimposing the model pattern and the detected pattern and treating the mismatched portion as a defect, or a method of determining the characteristics of the pattern from both the model pattern and the detected pattern. for example,
(Fig. 2) where there are minute parts in the pattern as shown in 10α and 10b, or right-angled parts such as 11α to llj) are extracted, and the features are compared, and a certain feature is found on one side. However, various methods have been devised and put into practice, such as a method in which a part is determined to be normal when the same feature exists in the other corresponding part, and a defect is determined otherwise.

However, none of the above methods can be said to be perfect, and defects may be overlooked or normal patterns may be incorrectly determined to be defects. For example, as shown in FIG. 3, the actual pattern (b) is often more rounded than the model pattern (a) due to various factors during mask manufacturing. In such a case, it will be determined that there is a defect using any of the defect determination methods described above, but in reality, if the roundness is of no practical use, it must be accepted as a normal pattern. be. For this reason, in actual mask pattern inspection, after a mask is inspected using a defect inspection device, defects are manually checked again on the mask to be inspected based on the inspection results to complete the inspection. Therefore, the problem is that it requires a lot of effort and pre-examination when confirming this defect. When confirming defects, the mask to be inspected is mounted on the X-Y stage of the inspection equipment main body, and this X-Y stage is moved to the position of the defect coordinates output as the inspection result, and each defect is identified one by one. However, a microscope is used to confirm whether or not it is a true defect. Alternatively, the detection pattern corresponding to the defect coordinates and the model pattern are displayed simultaneously on a display, etc., and the two are compared to confirm the defect. At this time, the model pattern is projected on the display, etc. at the same time as the detection pattern First, it is necessary to generate a model pattern again using the model pattern generator based on the defect coordinates. In addition, if a one-dimensional image sensor is used to detect the pattern, move the stage or image sensor to obtain a two-dimensional detection pattern, or install a galvano mirror or the like in the optical path between the mask and the image sensor. Rotate the galvano mirror 2
It is necessary to take measures such as detecting it as a dimensional image, which complicates the device configuration and inevitably increases costs. Furthermore, in any of the above-mentioned methods, the main body of the inspection apparatus must be used for human confirmation of defects, which is a major obstacle to improving the throughput of the inspection apparatus.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to eliminate the above-described drawbacks of the prior art, to provide a pattern inspection apparatus that allows easy manual pattern confirmation and has high inspection throughput.

[Summary of the invention]

In order to achieve this objective, in the present invention, when a defect determination device compares a sample pattern and a detected pattern and determines that there is a defect, it not only stores the coordinates on the mask where the defect exists, but also stores the coordinates of the defect on the mask. The feature is that it is possible to store surrounding images including both the model pattern and the detected pattern. After the inspection is complete, if you record all the memorized images of the detected defects on a magnetic tape, you can easily check the detected defects using another computer system, etc., without using the inspection equipment itself. throughput can be improved.

Note that while the control device is reading image data to store surrounding images including defects, the detection pattern and model pattern data are stored in the buffer memory to prevent pattern data from disappearing during this period. This prevents uninspected areas from occurring.

[Embodiments of the invention]

The present invention will be explained in detail below using examples.

FIG. 4 shows an embodiment of a pattern inspection device according to the present invention, and the structure up to obtaining a detection pattern and a model pattern is the same as that of the conventional device shown in FIG. 1, and is omitted. . The detection pattern signal that is the output of the image sensor is input to the buffer memory 161, which is a memory for temporarily pooling image data within a certain period of time from the buffer 7 memory 1J161 to 1677L connected in tandem. One of the contents of the memories 161 to 16rIL or the detection pattern signal itself is selected by the multiplexer 15 and input to the defect detection circuit 17 and the image memory 20. On the other hand, the model pattern signal from the model pattern generator is also sent to the back 7 memory 1.
91 to 19m in sequence, and the multiplexer 18 is
Either one of the model pattern and the contents of the buffer memos IJ191 to 19riL is selected and input to the defect detection circuit 17 and the image memory 20. The contents of the image memory 20 are constantly rewritten in response to input, and at a certain point both the inspection pattern and the model pattern of the screen including the area being inspected by the defect detection circuit 17 at that time are rewritten. Stored. Therefore, when a defect is not detected in the initial state or for a certain period of time, the control device 22 is informed by the signal C1, and outputs the signal C2 so that the multiplexers 15 and 18 select the detection pattern signal and the model pattern, respectively. There is. In this state, the defect detection circuit 17 continues to compare the detected pattern signal and the model pattern signal.

When a defect is detected by the defect detection circuit 17, the control device 22
This is notified by signal C1, and multiplexers 15 and 18 stop transferring data to defect detection circuit 17 and image memo 1J20. Further, the control device 22 records the coordinates of the defect just detected based on the signal C1 from the defect determiner 17, and issues a command C3 to the DMA controller 21 to cause the contents of the image memory 2o to be DMA-transferred to the magnetic disk 23. During this image data transfer period, detection patterns and model patterns are input at regular intervals, and these are stored in the back 7 memory 16.
1~1677L, 191~19mK are stored and preserved without being lost. When the DMA transfer is completed, the control device 22 can determine up to which buffer each pattern is stored based on the pattern input period (known), so the most advanced buffers 16t and 19i()゛〉t are stored in the buffer 16.

The multiplexers 15 and 18 are made to select the screen (no screen is included in No. 19) and continue the defect inspection. If the time required for one defect inspection is shorter than the inspection and model pattern input cycle, the buffers 161-16m, 191-19 are used as long as defects are not detected frequently.
The number of patterns temporarily stored in m will decrease as the test ends, so if you prepare a certain number of buffers m, the detected patterns will not disappear without being tested, thus creating a non-test area. No worries.

When all the inspections for one mask are completed as described above, if the contents of the magnetic disk 23 are transferred to the magnetic tape 24 etc. under the control of the control device 22, the defect confirmation work can be carried out by other computer systems etc. Since the screens of this magnetic tape can be compared visually, the inspection device can inspect other masks, and its throughput can be improved.

〔Effect of the invention〕

As is clear from the above embodiments, according to the present invention, the throughput of the inspection apparatus can be greatly improved by simply adding a simple circuit to the conventional defect detection circuit. Furthermore, since no special equipment configuration is required for performing defect confirmation work, it is also effective in reducing the cost of inspection equipment.

[Brief explanation of the drawing]

Figure 1 is a diagram showing an example of a conventional pattern inspection device;
FIG. 3 is an explanatory diagram of the defect detection principle using the feature extraction method, FIG. 3 is an explanatory diagram of a cause of erroneous detection of defects, and FIG. 4 is a diagram showing an embodiment of the present invention. 15, 18...Multiple flexors 161 to 16m...Back 7 memory 17...Defect detection circuits 191 to 19F7L...Back 7 memory 20...Image memory 21...DMA controller 22... Control device, 23...Magnetic disk 24...Magnetic tape. 2nd evil 3rd

Claims (1)

[Claims] The pattern to be inspected is imaged while being scanned two-dimensionally,
a scanning imaging unit that sequentially sends out the video signals; a model pattern generation unit that sequentially generates model pattern data corresponding to the pattern to be inspected based on pre-stored reference data; and a pattern to be inspected. In a pattern inspection device comprising a defect detection section that detects a defect by comparing the video signal of the above with the model pattern data, and a control section that performs necessary control over each of the above sections, the image of the pattern to be inspected is an image memory for temporarily storing the signal and the model pattern signal, a transfer control section for transferring the contents of the image memory to a secondary memory provided in the control section, and from the image memory to the control section. A buffer memory is provided for storing the video signal of the pattern to be inspected and the model pattern data generated during the transfer period of the pattern data to the inspection pattern, and when the defect determination section detects a defect in the inspection pattern, the buffer memory is provided. Controlling the transfer control unit to store not only the coordinate position where the defect exists, but also the surrounding image data including the defect, together with the corresponding model pattern in the secondary memory of the control unit, and after the transfer is completed; The control unit has a function of reading out the inspection target pattern video signal and the corresponding model pattern data stored in the buffer memory and controlling the defect determination unit to perform the next defect inspection. A pattern inspection device featuring: