JPS6314496B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a device for inspecting pattern defects on patterned bodies such as semiconductor chips and printed circuit boards, and for displaying abnormal areas. , is characterized in that it judges the input processing result of the pattern and displays it in a color that can be clearly distinguished from the normal part so that it can be seen at a glance.

An example of an apparatus for inspecting pattern defects in a semiconductor chip of a semiconductor integrated circuit will be described below.

FIG. 1 is a block diagram showing the configuration of an example of a conventional pattern defect inspection apparatus. In the same figure,
1 is a microscope; 2 and 3 are respectively an objective lens and an eyepiece of the microscope 1; 4 is a holding pedestal that holds the microscope 1 so that it can be moved up and down; 5 is attached to the holding pedestal 4 on which an IC chip 100 to be inspected is placed. A sample table 6 is provided with a table 5a of the test table 5 so as to be movable back and forth, and a table 5a of the test table 5 is moved.
8a, 8b and 8c are adjustment mechanisms for adjusting the focus of the objective lens 2 on the IC chip 100 to be inspected by moving the microscope 1 mounted on the holding frame 4 up and down; This is a reflecting mirror for taking out an image of the pattern of the inspection IC chip 100 from inside the microscope 1 to the outside. Reference numeral 9 indicates a receiver movement control circuit that controls the receiver moving mechanism 6; 10 indicates a focus adjustment control circuit that controls the focus adjustment mechanism 7; and 11.
has a TV camera, and from inside the microscope 1, the reflector 8
The test object taken out through a, 8b and 8c
A photoelectric conversion circuit converts the pattern image of the IC chip 100 into an image signal and outputs it; 12 is an image signal amplification circuit that amplifies and outputs the image signal output by the photoelectric conversion circuit 11; 13 is an image signal amplification circuit 12
An A/D conversion circuit 14 converts the image signal outputted from the image signal amplification circuit 12 into a digital image signal, and an A/D conversion circuit 14 divides the image signal outputted from the image signal amplification circuit 12 into a plurality of partial image signals, and converts these partial image signals into a digital image signal. 15 is a processing screen determination circuit that determines and outputs a portion of the image signal outputted from the image signal amplification circuit 12 that corresponds to the processing screen;
16 is a photoelectric converter 11, an image signal amplification circuit 12,
17 is an A/
From the digital image signal output by the D conversion circuit 13, the length, area,
An image analysis circuit 18 extracts and processes data signals of feature parameters such as shape, and 18 is a temporary storage device that stores data signals of feature parameters extracted and processed by the image analysis circuit 17. Note that this temporary storage device 18 also stores in advance data signals of characteristic parameters of patterns of standard IC chips 100 without defects. 19 is based on the image quantization signal outputted from the quantization processing circuit 14, the processing screen corresponding image signal outputted from the processing screen determining circuit 15, and the feature parameter data signal outputted from the image analysis circuit 17. This is an arithmetic processing circuit that performs arithmetic processing to determine the length, area, shape, etc. necessary for pattern recognition of the IC chip 100 to be inspected. This arithmetic processing circuit 19 uses the numerical value obtained through predetermined arithmetic processing and the standard IC chip 10 stored in the temporary storage device 18 in advance.
The comparison result is displayed as a message on a display device 20 such as a printer or a plotter, and is also displayed as an image on a TV cathode ray tube 21 for a monitor, and the calculation is performed at the same time. A control signal associated with the termination is output to the platform movement control circuit 9 and the focus adjustment control circuit 10.

Next, the operation of this conventional example will be explained. First, the IC chip 10 to be tested is placed on the mounting part 5a of the sample stage.
0 and sends a control signal to the receiver movement control circuit 9 and focus adjustment control circuit 10, the receiver movement control circuit 9 moves the receiver 5a via the receiver moving mechanism 6.
100 IC chips to be tested by moving the
is placed at a predetermined position with respect to the objective lens 2, and the focus adjustment control circuit 10 adjusts the focus of the objective lens 2 on the IC chip 100 to be inspected via the focus adjustment mechanism 7.

Next, a pattern image of the IC chip 100 to be inspected is taken out from inside the microscope 1 via reflecting mirrors 8a, 8b, and 8c, and converted into an image signal by a photoelectric conversion circuit 11.

Next, this image signal is transmitted to the image signal amplification circuit 12.
The amplified image signal is converted into a digital image signal by the A/D conversion circuit 13, and is divided into a plurality of sub-image signals by the quantization processing circuit 14, and quantized for each sub-image signal. At the same time,
The processing screen determining circuit 15 determines the portion of this amplified image signal that corresponds to the processing screen. During this time, the operations of the photoelectric conversion circuit 11, image signal amplification circuit 12, A/D conversion circuit 13, quantization processing circuit 14, and processing screen determination circuit 15 are synchronized with the synchronization signal output from the synchronization signal generation circuit 16. . Next, a data signal of the characteristic parameters of the pattern of the IC chip 100 to be inspected is output from the digital image signal converted by the A/D conversion circuit 13 to the image analysis circuit 17.
The data is extracted and stored in the temporary storage device 18. Thereafter, in the arithmetic processing circuit 19, based on the image quantization signal from the quantization processing circuit 14, the processing screen corresponding image signal from the processing screen determination circuit 15, and the feature parameter data signal from the image analysis circuit 17, The predetermined arithmetic processing is performed and the
Numerical values necessary for recognizing the pattern of the IC chip 100 are calculated. The numerical value obtained through this arithmetic processing is then compared with the numerical value calculated from the data signal of the characteristic parameter of the pattern of the standard IC chip 100 stored in the temporary storage device 18 in advance. For example, a standard IC chip 1 stored in the temporary storage device 18 and whose plan view is shown in FIG.
The numerical values calculated from the data signals of the characteristic parameters of the defect-free aluminum (Al) wiring film 101a of 00a and the test object whose plan view is shown in FIG. 2B.
When compared with the numerical value calculated from the data signal of the characteristic parameter of the Al wiring film 101b having defects in the S and D parts of the IC chip 100b shown in the figure, The value in the section is standard IC chip 100a
Since the values are different from those in the parts corresponding to the S part and D part of the Al wiring film 101a, IC chip 1
Defects in the S part and the D part of the Al wiring film 101b of 00b are detected. And these defects are
A message indicating that there is a defect is displayed on the display device 20, and an image is displayed on the TV cathode ray tube for monitoring.

By the way, in the conventional device, when there is a defect,
The message was displayed in text, or the processed result was displayed as a pattern diagram. When displaying in text like this, you can immediately tell that there is a defect, but you cannot immediately see its location. Furthermore, when displayed as a pattern diagram, it is difficult to locate the defect. In addition, since the inspection criteria for inspecting pattern defects in conventional examples is fixed by image processing hardware, it is not easy to change the inspection criteria, and the hardware configuration is complicated and expensive. There were drawbacks such as high cost.

This invention was made in view of the above points,
By performing image processing using software using a computer, the inspection criteria for inspecting pattern defects can be easily changed, and
The object of the present invention is to provide an inexpensive pattern defect display device that facilitates identification by controlling defective portions using color codes.

FIG. 3 is a block diagram showing the structure of a pattern defect display device according to an embodiment of the present invention. In the same figure, the same reference numerals as in the conventional example shown in FIG. 1 indicate the same parts, and the explanation thereof will be omitted. 22 is A/D
A central processing unit (hereinafter referred to as "CPU") that performs image processing of the digital image signal output from the conversion circuit 13. 23 is an input device for key-inputting control commands to the CPU 22, and 24 stores a series of control programs for the CPU 22 to perform image processing.
ROM, 25 is a standard storage device for storing the image quantization signal of the standard IC chip 100, 26 is a temporary storage device for storing the quantization signal of the pattern of the IC chip 100 to be inspected, and 27 corresponds to the color specified in the color code memory. This is a color code memory where codes are stored. Reference numeral 28 denotes an auxiliary storage device such as a magnetic tape or a magnetic disk, which is used when the standard storage device 25 and the temporary storage device 26 overflow or to store additional data signals.

Next, the operation of this embodiment will be explained. First, the standard IC chip 100 is placed on the mounting section 5 of the sample stage 5.
a, and when an operation command is entered from the input device 23 to the CPU 22, a control signal is output from the CPU 22 to the mounting section movement control circuit 9 and the focus adjustment control circuit 10. The placing part movement control circuit 9 moves the placing part 5a back and forth and left and right through the placing part moving mechanism 6 to place the standard IC chip 100 at a predetermined position with respect to the objective lens 2, and the focus adjustment control circuit 10 moves the placing part 5a back and forth and left and right. The focus of the objective lens 2 on the standard IC chip 100 is adjusted via the focus adjustment mechanism 7. Next, an image of the pattern of the standard IC chip 100 is transmitted from inside the microscope 1 to the reflecting mirrors 8a and 8.
b and 8c to the photoelectric conversion circuit 1
1, it is converted into an image signal. This image signal is amplified by an image signal amplification circuit 12, and this amplified image signal is converted into a digital image signal by an A/D conversion circuit 13 and output to the CPU 22 through an input port. During this time, the operations of the photoelectric conversion circuit 11, the image signal amplification circuit 12, and the A/D conversion circuit 13 are each synchronized by a synchronization signal output from the synchronization signal generation circuit 16. Next, the A/D conversion circuit 13
Standard IC chip 100 outputted to CPU22 from
In the CPU 22, the image quantized signal is stored in the standard storage device 25 according to the control program stored in the ROM 24.
is stored in

In this way, with the image quantized signal of the standard IC chip 100 stored in the standard storage device 25, the IC chip 100 to be tested is placed on the mounting portion 5a of the sample stage 5, and the image quantized signal is input from the input device 23. When the operation command is inputted to the CPU22 by key, the above-mentioned standard IC
The same functional operation as in the case of the chip 100 is performed, and the IC chip 1 to be tested is transferred from the A/D conversion circuit 13.
00 pattern digital image signal is sent to CPU22
output through the input port. and,
In the CPU 22, this digital image signal is
According to the control program stored in the ROM 24, it is stored in the temporary storage device 2 as a quantized image signal. Subsequently, the image quantization signal stored in this temporary storage device 26 and the image quantization signal stored in the standard storage device 25 are compared.
At this time, if a defect different from that of the standard storage device 25 is detected, the abnormality flag will be set to the CPU 2.
The color code memory 27 is accessed by the signal generated based on the register 2, and the data is sent to the output port for monitoring.
It controls the color control section of the TV cathode ray tube 21 and outputs the specified color. For example, as shown in FIG. 4A of the defect-free Al wiring film 101a of the standard IC chip 100a whose plan view is shown in FIG. 2A,
The image quantized signal stored in the standard storage device 25 and the IC chip 10 to be tested whose plan view is shown in FIG. 2B.
The image quantized signal stored in the temporary storage device 26 is compared with the image quantized signal as shown in FIG. At this time, the code in the shaded area in FIG. 4B corresponds to the defective parts S and D in FIG. 2B, so when a defect is detected, the color code memory 27 is accessed as described above. The color control unit of the monitor TV cathode ray tube 21 is controlled to display the defective part in a prespecified color. Therefore, defective parts can be clearly displayed at a glance.

In this way, in the device of this embodiment, CPU2
Image processing according to 2 is generally performed according to the control program stored in the ROM 24, so unlike the conventional example shown in FIG. By changing only the control program, it is possible to change the image size, etc., and by specifying data, it is possible to change the color code for displaying defective parts, and the inspection criteria for pattern defects can be easily changed. Furthermore, the configuration of image processing by the CPU 22 is simple and the price is low. In this embodiment, the case where image processing is performed on the pattern of the IC chip 100 to be inspected has been described, but when the characteristic parameters of the IC chip 100 to be inspected are extracted and image processed as in the conventional example shown in FIG. However, it goes without saying that this embodiment has the same effect as this embodiment. Also,
Defects can also be classified by color by specifying a color code. Furthermore, it can be displayed not only on a TV cathode ray tube, but also on a printer, plotter, etc. as necessary. So far, 100 IC chips
The pattern defect display device was described as an example;
The present invention is not limited to this, and can be applied to inspecting and displaying defects in printed circuit boards and other pattern-formed bodies.

As explained above, in the pattern defect display device of the present invention, the digital image signal corresponding to the pattern of a standard patterned body without defects is used.
Image processing is performed according to the control program of the standard image data signal obtained by performing image processing according to the control program stored in the ROM and the digital image signal corresponding to the pattern of the pattern-formed body to be inspected. software processing to detect defects in the pattern of the patterned body to be inspected and to clearly display the defective parts by specifying a color code. The above method can be performed without changing the hardware that performs image processing as in conventional examples.
By simply changing the control program stored in the ROM or data in the specified code, inspection standards for pattern defects on the patterned body can be easily changed, and defective parts can be displayed in a way that allows identification. . Furthermore, the above image processing configuration is simple and inexpensive.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an example of a conventional device.
2A and 2B are plan views showing an example of a standard IC chip and an IC chip to be inspected, respectively; FIG. 3 is a block diagram showing the configuration of a pattern defect display device according to an embodiment of the present invention; FIG. 4A is stored in the standard storage device of the above embodiment, and is stored in the standard IC of FIG. 2A.
A diagram showing an example of an image quantized signal corresponding to the chip Al wiring film, FIG. 4B is stored in the temporary storage device of the above embodiment,
FIG. 3 is a diagram showing an example of an image quantized signal corresponding to a wiring film. DESCRIPTION OF SYMBOLS 1... Microscope, 2... Objective lens, 3... Eyepiece, 4... Holding stand, 5... Sample stand, 5a...
... Placement section, 6 ... Placement section moving mechanism, 7 ... Focus adjustment mechanism, 100 ... IC chip, 8a, 8b, 8
c...Reflector, 9...Placement section movement control circuit, 10
... Focus adjustment control circuit, 11 ... Photoelectric conversion circuit,
12... Image signal amplification circuit, 13... A/D conversion circuit, 14... Quantization processing circuit, 15... Processing screen determination circuit, 16... Synchronization signal generation circuit, 17...
...Image analysis circuit, 18...Storage device, 19...Arithmetic processing circuit, 20...Display device, 21...TV cathode ray tube, 22...CPU, 23...Key input device, 24...ROM, 25... Standard storage device, 2
6... Temporary storage device, 27... Color code memory,
28... Auxiliary storage device.

Claims (1)

[Claims] 1. A photoelectric conversion circuit that converts the image of the pattern of the pattern forming body into an image signal and outputs it, an A/D conversion circuit that converts the image signal outputted by this photoelectric conversion circuit into a digital image signal and outputs it, and this A/D conversion circuit. /D
a central processing unit that performs image processing on digital image signals output by the conversion circuit according to a control program; a read-only memory that stores the control program; a standard storage device that stores standard image data obtained by converting it into a digital image signal through the A/D conversion circuit and performing image processing; , a temporary storage device for temporarily storing an image to be inspected obtained by converting it into a digital image signal through the A/D conversion circuit and performing image processing, and storing the image in the ROM in the central processing unit. The standard image data stored in the standard storage device according to the control program and the image data to be inspected stored in the temporary storage device are compared to detect defects in the pattern of the patterned body to be inspected. 1. A pattern defect display device characterized in that when a pattern defect is detected, the defect is replaced with a specified color and displayed by accessing a memory that stores a specified color code.