JP2003229462A - Circuit pattern testing apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a circuit pattern testing apparatus which facilitates convenient and rapid creation of a recipe, comparison and display of images, setting of test regions, or other operations. <P>SOLUTION: In the circuit pattern testing apparatus 1, when performing a test, with a created recipe applied to a plurality of wafers, the recipe is copied from one shelf number to another shelf number on a graphic screen display of a cassette wherein the wafers are held. A defect information file from another testing apparatus is retrieved, and based on the content of the file, a new recipe for the circuit pattern testing apparatus 1 is created. Moreover, from the results of merging of test results or overlapping of dies and shots, areas which require no test are assigned using graphics on the screen to create new test areas or change the test areas. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pattern inspection technique for semiconductor devices and photomasks, and more particularly to a technique for comparative inspection using an electron beam.

[0002]

2. Description of the Related Art As a method for inspecting a defect existing in a pattern on a semiconductor wafer, there is a defect inspection apparatus which irradiates a semiconductor wafer with white light and compares circuit patterns of the same kind of a plurality of LSIs using an optical image. It has been put to practical use.
The outline of the inspection method is "Monthly Semiconductor World" 19
It is described in the August 1995 issue, pp96-99.

When a semiconductor wafer is inspected in the manufacturing process by such an optical inspection method, a residue or a defect of a pattern having a silicon oxide film or a photosensitive photoresist material on the surface through which light is transmitted cannot be detected. It was In addition, it was not possible to detect an etching residue or a non-opening defect of a minute conductive hole, which is lower than the resolution of the optical system. Further, the defect generated at the bottom of the step of the wiring pattern could not be detected.

In recent years, with the miniaturization of circuit patterns, the complexity of circuit pattern shapes, and the diversification of materials, it has become difficult to detect defects by optical images. Therefore, electron beam images having higher resolution than optical images are used. A method of comparing and inspecting circuit patterns has been proposed. In order to obtain a practical inspection time when performing a comparative inspection of circuit patterns using electron beam images, a scanning electron microscope (Scanning Electron Microscop
y, hereinafter abbreviated as SEM) It is necessary to acquire images at a much higher speed than observation by observation. Then, it is necessary to secure the resolution of the image acquired at high speed and the SN ratio of the image.

As a pattern inspection device using an electron beam, J. Vac. Sci. Tech. B, Vol. 9, No. 6, pp. 3005-3009
(1991), J.Vac.Sci.Tech.B, Vol.10, No.6, pp.2804-280.
8 (1992), JP-A-5-258703 and USP 5,502,306. Here, 100 times more than a normal SEM (10n
An electron beam having an electron beam current of A or higher) is applied to the conductive substrate to detect any of secondary electrons, backscattered electrons, and transmitted electrons, and the image formed from the signals is compared and inspected automatically. A detection method is disclosed.

As a method for inspecting or observing a circuit board having an insulator with an electron beam, there are JP-A-59-155941 and "Electron, Ion Beam Handbook" (Nikkan Kogyo Shimbun) pp622-623. In order to reduce the influence of charging, a method of obtaining a stable image by low-acceleration electron beam irradiation of 2 keV or less is disclosed. Further, Japanese Patent Application Laid-Open No. 2-15546 discloses a method of irradiating ions from the back of a semiconductor substrate, and Japanese Patent Application Laid-Open No. 6-338280 discloses that the surface of a semiconductor substrate is irradiated with light to cancel the charging of an insulator. A method is disclosed.

An electron beam with a large current and a low acceleration makes it difficult to obtain a high resolution image due to the space charge effect. As a method for solving this, Japanese Patent Application Laid-Open No. 5-258703 discloses a method of decelerating a high-acceleration electron beam immediately before the sample and irradiating the sample with a substantially low-acceleration electron beam.

As a method for acquiring an electron beam image at high speed, there is a method of continuously irradiating an electron beam on a semiconductor wafer on the sample stage while continuously moving the sample stage to obtain the electron beam image.
It is disclosed in JP-A-59-160948 and JP-A-5-258703.

[0009]

In the above-mentioned conventional inspection apparatus, the screen function of the wafer visual inspection apparatus has not been sufficiently taken into consideration. JP2000-
Japanese Patent No. 193594 (hereinafter, referred to as a publicly known example) describes an operation screen display method, an inspection using the operation screen, an inspection condition setting method, and the like, so that condition setting for efficient inspection can be executed in a short time. Technology is shown.

The object of the present invention is to improve the screen function for copying a recipe not taken into consideration in the above cited publicly known examples, using a recipe of another semiconductor device, displaying a defect image, and designating an inspection area. The purpose is to provide a circuit pattern inspection device that is easy to use.

[0011]

SUMMARY OF THE INVENTION To achieve the above object, the present invention provides an irradiation means for irradiating a substrate surface on which a circuit pattern of a wafer is formed with light, laser light or a charged particle beam,
A detection unit that detects a signal generated from the substrate by the irradiation, a storage unit that images and stores the signal detected by the detection unit, and a reference image formed from the same circuit pattern as the stored image. Comparison means to compare,
In the circuit pattern inspection device equipped with the determination means for determining the defect on the circuit pattern from the comparison result, when performing the inspection on a plurality of wafers by the already created recipe, the shelf number of the cassette containing the wafers is set. A screen operation unit for copying, moving, or deleting a recipe from one shelf number to another shelf number is provided on the screen shown.

Further, the circuit pattern inspection device of the present invention reads a defect information file inspected by a recipe creating function for creating a recipe and other information, and then, the wafer matrix information, inspection area information, and alignment position information are read. A screen operation unit having a conversion function for converting information for the inspection device is provided, and the converted data is input to the recipe creating function to create a new recipe for the inspection device.

Further, it is characterized in that a screen operation unit is provided for displaying the image of the defect and the image of the normal portion for comparison with the same display device. The screen operation unit simultaneously displays images of defects and normal areas. Alternatively, the image of the defect and the image of the normal portion are alternately displayed at preset time intervals.

Further, in order to change the angle of the image irradiated with the electron beam on the sample, an angle changing means for changing the angle of the electron beam or the sample table, and two or more images acquired by changing the angle are provided. An image display unit for stereoscopically displaying a defect image by simultaneously displaying on the same display device is provided.

Further, in order to determine the brightness of the image at the time of the inspection, a screen operation unit for displaying the histogram of the brightness of the acquired image and changing the brightness of the histogram data is provided. .

Further, it is characterized in that a screen operation section is provided for superposing the inspection results on each die or each shot and designating an overlapping area from the defect distribution as an inspection unnecessary area.

In addition, when the die area and the cell area are inspected by die comparison, a screen operation unit for excluding the periphery of the cell area as an inspection unnecessary area is provided.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of a circuit pattern inspection device according to the present invention will be described below in detail with reference to the drawings. In this embodiment, the resist pattern, CON
It targets defects such as T-based opening patterns, fine patterns after etching (diffusion type), and fine patterns after etching (wiring type).

FIG. 1 shows the configuration of a circuit pattern inspection device. The circuit pattern inspection apparatus 1 includes an inspection chamber 2 in which the chamber is evacuated, and a spare chamber (not shown in this embodiment) for transporting the substrate 9 to be inspected into the inspection chamber 2. The chamber is constructed so that it can be evacuated independently of the inspection chamber 2. The circuit pattern inspection apparatus 1 is composed of a control unit 5 and an image operation unit 6 in addition to the inspection chamber 2 and the preliminary chamber.

The inspection chamber 2 is roughly divided into an electron optical system 3, a secondary electron detector 7, a sample chamber 8 and an optical microscope 4. The electron optical system 3 includes an electron gun 10, an electron beam extraction electrode 11, a condenser lens 12, a blanking deflector 13, a scanning deflector 15, a diaphragm 14, an objective lens 16, a reflecting plate 17, and an ExB deflector 18. It forms the irradiation means. The secondary electron detector 20 of the secondary electron detector 7 is arranged above the objective lens 16 in the examination room 2. The output signal of the secondary electron detector 20 is amplified by a preamplifier 21 installed outside the inspection room 2 and becomes digital data by an AD converter 22. The sample chamber 8 includes a sample stage 30, an X stage 31, a Y stage 32, a rotary stage 33, a position monitor length measuring device 34, and an inspected substrate height measuring device 3.
It is composed of 5.

The optical microscope unit 4 includes a light source 40 and an optical lens 4.
1, the CCD camera 42, and is installed in a position near the electron optical system 3 in the room of the inspection room 2 and apart from each other to the extent that they do not affect each other. The distance between is known.

The X stage 31 or the Y stage 32 is
The electronic optical system 3 and the optical microscope unit 4 can be moved back and forth over a known distance. In addition, the rotary stage 33
Alternatively, the sample table may be tilted at any side thereof so that the electron beam 19
May be configured so that the angle of irradiation of the sample 9 can be changed.

The control unit 5 comprises an overall control unit 49 and the following devices. A storage unit 45 for converting an analog signal from the secondary electron detection unit 7 into a digital signal and storing the digital signal, an image processing circuit 46 for processing the stored digital signal,
The image processing circuit 46 has an inspection condition setting unit 48 for setting processing parameters, and a defect data buffer 47 for holding defect information as a processing result of the image processing circuit 46.

The image operation section 6 includes a first image storage section 51, a second image storage section 52, a comparison calculation section 53, and a defect determination processing section 5.
4, the image display unit 56 arbitrarily selects and displays an electron beam image, a defect image, or the like. Further, it is provided with a map display unit 55 for displaying the position of the sample and giving a movement instruction, an image acquisition instruction unit 57, an image processing instruction unit 58, and a processing condition setting unit 59. Further, it has a mode switching unit 60 for dividing the mode according to the operation content.

Operation commands and operation conditions of each part of the apparatus are input and output from the control part 5. In the control unit 5, conditions such as an acceleration voltage at the time of electron beam generation, an electron beam deflection width, a deflection speed, a signal acquisition timing of a secondary electron detection unit, and a sample stage moving speed are input so that they can be set according to the purpose. ing.

The control unit 5 uses the correction control circuit 61 to monitor the position and height deviations from the signals from the position monitor length measuring device 34 and the inspection board height measuring device 35, and generates a correction signal from the result. , A correction signal is sent to the objective lens power supply 44 and the scanning signal generator 43 so that the electron beam is always irradiated to the correct position.

In order to acquire an image of the board 9 to be inspected,
The primary electron beam 19 that is narrowed down is applied to the substrate 9 to be inspected,
By generating the secondary electrons 51 and detecting them in synchronization with the scanning of the primary electron beam 19 and the movement of the stages 31 and 32, an image of the surface of the substrate 9 to be inspected is obtained.

As described above, a high inspection speed is essential for the automatic inspection of the present invention. Therefore, normal SEM
As described above, an electron beam having an electron beam current on the order of pA is not scanned at low speed, a large number of scans, or superposition of images is not performed. Further, in order to suppress the charging of the insulating material, it is necessary to perform electron beam scanning at high speed once or several times.

In this embodiment, about 100 is used as compared with a normal SEM.
An image is formed by scanning a high current electron beam of, for example, 100 nA or more twice, only once. The scanning width was 100 μm, and one pixel was 0.1 μm ^2, and one scan was performed in 1 μs.

A diffusion replenishment type thermal field emission electron source is used for the electron gun 10. By using this electron gun 10, a stable electron beam current can be secured as compared with a conventional tungsten (W) filament electron source and a cold field emission type electron source, and thus an electron beam with less fluctuation in brightness. An image is obtained. Further, since the electron beam current can be set large by the electron gun 10, high speed inspection can be realized.

The primary electron beam 19 is extracted from the electron gun 10 by applying a voltage between the electron gun 10 and the extraction electrode 11. The primary electron beam 19 is accelerated by the electron gun 10.
This is done by applying a high voltage negative potential to. The primary electron beam 19 has energy corresponding to the electric potential, and the sample table 30
In the X direction on the sample table 30 after being converged by the condenser lens 12 and further narrowed down by the objective lens 16.
-Inspected board 9 mounted on Y stages 31 and 32
Is irradiated. The substrate 9 to be inspected is a semiconductor wafer, a chip or a substrate having a fine circuit pattern such as a liquid crystal or a mask. The blanking deflector 13 includes a scanning signal generator 4 for generating a scanning signal and a blanking signal.
3 is connected, and a lens power supply 44 is connected to each of the condenser lens 12 and the objective lens 16.

The substrate 9 to be inspected has a retarding power source 3
A negative voltage is applied by 6. By adjusting the voltage of the retarding power supply 36, the primary electron beam can be decelerated and the electron beam irradiation energy to the inspected substrate 9 can be adjusted to an optimum value without changing the potential of the electron gun 10.
Secondary electrons 51 generated by irradiating the inspected substrate 9 with the primary electron beam 19 are accelerated by the negative voltage applied to the inspected substrate 9.

An ExB deflector 18 is provided above the substrate 9 to be inspected.
The secondary electrons 51 thus accelerated are deflected in a predetermined direction. The deflection amount can be adjusted by the voltage applied to the ExB deflector 18 and the strength of the magnetic field. Further, this electromagnetic field can be varied in association with the negative voltage applied to the sample. The secondary electrons 51 deflected by the ExB deflector 18 collide with the reflecting plate 17 under a predetermined condition. The reflector 17 has a conical shape integrally with a shield pipe of a deflector for an electron beam (hereinafter referred to as a primary electron beam) that irradiates the sample. When the accelerated secondary electrons 101 collide with the reflecting plate 17, several eV to
A second secondary electron 102 having an energy of 50 eV is generated.

The secondary electron detector 7 has a secondary electron detector 20 inside the vacuum-exhausted inspection chamber 2. Outside the inspection room 2, a preamplifier 21, an AD converter 22, a light conversion means 23,
There are optical transmission means 24, electrical conversion means 25, high voltage power supply 26, preamplifier drive power supply 27, AD converter drive power supply 28, and reverse bias power supply 29. As described above, the secondary electron detector 20 of the secondary electron detector 7 is arranged above the objective lens 16 in the examination room 2. Secondary electron detector 2
0, preamplifier 21, AD converter 22, optical conversion means 2
3, preamplifier drive power supply 27, AD converter drive power supply 28
Is floating at a positive potential by the high voltage power supply 26. Second secondary electrons 5 generated by collision with the reflector 17
2 is guided to the secondary electron detector 20 by this attracting electric field.

The secondary electron detector 20 includes the secondary electrons 1 generated while the primary electron beam 19 is irradiated on the substrate 9 to be inspected.
01 is configured to detect the second secondary electron 102 which is then accelerated and collides with the reflection plate 17 in association with the scanning timing of the primary electron beam 19.

The output signal of the secondary electron detector 20 is amplified by the preamplifier 21 installed outside the inspection room 2 and becomes digital data by the AD converter 22. AD converter 22
Is configured to convert the analog signal detected by the secondary electron detector 20 into a digital signal immediately after being amplified by the preamplifier 21 and to be transmitted to the control unit 5. Since the detected analog signal is digitized immediately after detection and then transmitted, a high-speed signal having a high SN ratio can be obtained.

A substrate 9 to be inspected is mounted on the XY stages 31 and 32, and when the inspection is performed, the XY stages 31 and 32 are stopped and the primary electron beam 19 is two-dimensionally scanned. Alternatively, when the inspection is executed, the XY stages 31, 3
It is possible to select either one in which the primary electron beam 19 is linearly scanned in the X direction while the 2 is continuously moved in the Y direction at a constant speed. When inspecting a certain relatively small area, the former stage is stationary and inspected,
When inspecting a relatively wide area, it is effective to move the stage continuously at a constant speed to inspect. In addition,
When it is necessary to blank the primary electron beam 19,
The blanking deflector 13 deflects the primary electron beam 19 so that the electron beam can be controlled so as not to pass through the diaphragm 14.

As the position monitor length measuring device 34, a length measuring device by laser interference is used in this embodiment. The positions of the X stage 31 and the Y stage 32 can be monitored in real time and transferred to the control unit 50. Further, data such as the number of revolutions of each motor of the X stage 31, the Y stage 32, and the rotary stage 33 is also configured to be similarly transferred from each driver to the control unit 5. Based on these data, the control unit 5 can accurately grasp the area or position where the primary electron beam 19 is irradiated. If necessary, the correction control circuit 61 corrects the positional deviation of the irradiation position of the primary electron beam 19 in real time. Further, the area irradiated with the electron beam can be stored for each inspected substrate.

The inspected substrate height measuring device 35 is an optical measuring device which is a measuring method other than the electron beam, such as a laser interferometer or a reflected light measuring device for measuring a change in the position of reflected light. There is. The height of the substrate 9 to be inspected mounted on the XY stage 31, 32 is measured in real time. In this embodiment, the elongated white light that has passed through the slit is irradiated onto the substrate 9 to be inspected through a transparent window, the position of the reflected light is detected by a position detection monitor, and the amount of change in height is calculated from the position change. The calculation method was used.

The focal length of the objective lens 16 for narrowing down the primary electron beam 19 is dynamically corrected on the basis of the measurement data of the substrate height measuring device 35 to be inspected, and the primary region is always focused on the non-inspection region. The electron beam 19 can be irradiated. It is also possible to measure the warpage and height distortion of the substrate 9 to be inspected before the electron beam irradiation, and to set the correction condition for each inspection region of the objective lens 16 based on the data. Is.

Next, the structure of the image operating section 6 will be described. The image signal of the substrate 9 to be inspected detected by the secondary electron detector 20 is amplified by the preamplifier 21, digitized by the AD converter 22, and then converted into an optical signal by the optical conversion means 23.
It is transmitted by the optical transmission means 24. Electrical conversion means 25
After being converted into an electric signal again at, the first image storage unit 51 of the image operation unit 6 is passed through the overall control unit 49 of the control unit 5.
Alternatively, it is stored in the second image storage unit 52.

The comparison / calculation unit 53 performs various image processes for aligning the stored image signal with the image signal in the other storage unit, standardizing the signal level, and removing noise signals. The image signals are compared and calculated. The defect determination unit 54 compares the absolute value of the difference image signal calculated by the comparison calculation unit 53 with a predetermined threshold value, and if the difference image signal level is higher than the predetermined threshold value, the pixel is selected. It is determined as a defect candidate, and the position, the number of defects, etc. are displayed on the image display unit 56.

Next, how to set the conditions at the time of inspection will be described. FIG. 2 shows the screen configuration of the image operation unit 6 and the initial screen of the examination. On this screen, a map display unit 55 showing the current position of the stage and an image display unit 56 displaying the light microscope image of the optical microscope unit 4 are shown. By clicking on the map display portion 55, the stage 31 or 32 is moved to select a place for setting conditions. In addition, by clicking the image acquisition support unit 57 of the image operation unit 6, the electron beam 19 is irradiated onto the inspected substrate 9 and the secondary electrons generated are detected by the secondary electron detector 20 and converted into digital signals. Then, a digital image of a predetermined area is acquired in the storage means 45.

The processing condition setting unit 59 of the image operating unit 6 sets the processing conditions, and the image processing instruction unit 58 is clicked. Furthermore, the inspection condition setting unit 48 of the control unit 5 is set, and the digital image stored in the storage unit 45 is set based on the setting conditions.
The image processing circuit 46 processes it to extract a defect and stores it in the defect buffer 47. In this way, the area where the image is acquired is enlarged and displayed on the map display unit 55 to visually recognize the position of the defect,
By clicking this position, the defect position storage means 4
The image on the screen 5 is displayed on the image display unit 56.

By repeating these operations, inspection conditions suitable for inspection are searched. When the condition confirmation at one place is completed, the map display portion 55 is again displayed in a reduced size, and the image display portion 5 is displayed.
6 is switched to the optical microscope image, the condition setting place is reselected, and the process from image acquisition to condition setting is repeated.

Next, various parameters necessary for executing the inspection in this embodiment will be described. The parameters include parameters specific to the board to be inspected and parameters that determine the operating conditions of the apparatus.

The parameters peculiar to the substrate to be inspected are roughly classified into two types. One is a parameter called a "product file", which is a parameter that does not change depending on the layer in the manufacturing process. For example, wafer size, orientation flat or notch shape, exposure shot size of semiconductor products, chip (die) size,
The memory cell area, the size of the repeating unit of the memory cell, and the like. These are tabulated as a "product file".

The other is a parameter called a "process file", which is a parameter that needs to be adjusted because the surface material and shape state differ depending on the layer during the manufacturing process. For example, electron beam irradiation conditions, various gains of the detection system, image processing conditions for detecting defects, etc. are registered as a “process file”.

At the time of inspection, by specifying the "product file" and the "process file", the inspection conditions corresponding to the specific semiconductor product and the specific manufacturing process can be called. In this embodiment, the "product file" and the "process file" are collectively referred to as "recipe". A series of operations for inputting / registering these various parameters is called “recipe creation”.

The recipe making method and the operation screen for executing the recipe will be described below. The screen of FIG. 2 is roughly divided into five areas. The area (1) is arranged at the upper part of the screen and displays the device name, the device ID, and the recipe file name and process file name as the recipe name. In the area (2), guidance for explaining operations and states is displayed.

In the area (3) at the center of the screen, the display content changes depending on the operation and the state of progress. In the area (4) on the right side of the screen, operation buttons commonly required for a plurality of screens are displayed, such as “print”, “file save”, “start”, “end”, and “image save”. For example, when "Save File" is pressed, a screen for designating the name of a product type file and a process file for saving the recipe currently being created is displayed. Also,
When "Save image" is pressed, a screen for specifying the name for saving the image currently displayed as an image file is displayed.

In the operation area (5) at the bottom of the screen, the mode name is displayed. For example, when "inspection" is pressed, the automatic inspection is performed, and when "recipe creation" is pressed, the above parameters are input.

FIG. 3 shows a processing flow of the recipe creation mode. When the "recipe creation" mode is selected on the initial screen of FIG. 2, the mode switching means 60 functions and switches to the screen for recipe creation shown in FIG. The start button is pressed on this screen, and the shelf number of the cassette is displayed. First, the shelf number is designated (S1). Next, call the recipe file and enter the product type condition, new or changed,
The lot ID and wafer ID are input (S2).

This change is a change in the recipe creation condition, irrespective of whether or not it is loaded, and is mainly a change made by loading. Note that the recipe for other devices, which will be described later, cannot be entered directly, so enter the inspection result file (defect information file: the contents of this file are open to the user) and convert it to create a recipe for your device. And modify it at this step to make up for the missing data.

Here, it is newly created, and then the wafer cassette is installed in the loader of the inspection apparatus (S3). As the item, (1) OF or notch is detected,
(2) Hold the sample holder (sample exchange chamber), and (3) transfer the sample holder to the inspection chamber stage.

Next, the stage is moved to the stage reference mark and the beam is calibrated absolutely (S4). Calibration is performed based on the default recipe file conditions, and (1) beam irradiation, (2) deflection correction, reference coordinate correction, and (3) focus parameter correction are performed.

Next, the designated position on the sample is irradiated with an electron beam to check the image contrast on the sample and readjust the focus and astigmatism (S5). At this time, if sufficient contrast cannot be obtained, the electron beam irradiation conditions are changed. Here, the specified irradiation condition, focus condition, and astigmatism condition are stored in the process file as recipe parameters.

When the electron beam irradiation condition is determined and the contrast is confirmed, the shot of the wafer and the size and arrangement of the die (chip) are input (S6). When the shot size and shot matrix are input, and the array of dies within the shot is input, the shot in the peripheral area of the wafer or the presence or absence of the die is specified. The shots and die array set here are stored as parameters in the recipe file.

Next, the alignment condition input and the alignment are executed (S7). (1) Alignment chip designation (multiple points), (2) Move to the origin of the 1st chip, (3)
Switch the optical microscope monitor, and (4) manually move to the alignment mark position of the first chip. (5) Register the optical image, (6) switch to SEM image mode, (7) finely adjust to the alignment mark position manually, (8)
SEM image registration and (9) alignment coordinate registration are performed.

As an item for executing alignment,
(1) first point movement, (2) image input / search / matching, (3) second point movement, (4) image input / search / matching, (5) movement to remaining point, search, matching, ( 6)
Correct tilt, position and chip interval.

As the chip origin offset setting, (1) move to the final point alignment mark, (2) specify the alignment mark position (SEM image mode),
(3) Move to the first point tip origin, (4) Tip origin position designation (SEM image mode), (5) Tip origin-Alignment mark offset calculation / registration. The chip origin offset is the distance between the alignment coordinates and the origin coordinates of the chip where the mark is located.

In this way, the offset value between the designated alignment pattern coordinate and the chip origin is input and registered as an alignment parameter in the process file. In the recipe creation, since there are many parameters that specify the coordinates for executing various processes on the wafer, the alignment conditions are first determined and registered, and the alignment is executed.

Next, the memory cell area in the chip is set (S8). The items are (1) cell area input,
(2) Cell pitch input, (3) (1), and (2) registration. Input of the cell region is performed using an optical microscope image and an electron beam image.

Next, the die area is set (S9). The items are (1) die area input, (2) die non-inspection area input, and (3) (1) and (2) registration. The input of the die area is also performed by using an optical microscope image and an electron beam image.

Next, the inspection area is designated (S10). When designating the inspection area, the inspection die and the inspection area
The type can be specified. If you don't need to inspect every die,
Further, when it is desired to inspect only a specific area in the die, it can be arbitrarily specified as described later. Further, the inspection sampling rate can be designated for the designated area. Also, the inspection direction can be specified. The data of the die area and the inspection area are stored as parameters in the process file.

When the designation of the inspection region is completed, the calibration setting for adjusting the brightness during the inspection is started (S1).
1). The calibration is to acquire an image and perform hardware gain adjustment and brightness correction according to the signal amount based on the brightness distribution. In practice, the die to be calibrated and the coordinates within the die are designated. The coordinate value for performing the calibration, the gain of brightness, and the offset value are stored as parameters in the process file.

Next, an image is actually acquired under the various conditions set so far, and image processing conditions for detecting defects are set (S12). First of all, when acquiring the image,
Select the type of filter applied to the detection signal. And
An image of a small area in one chip is actually acquired under the same conditions as the inspection. Here, the small area means, for example, an area having a width of 100 μm which is an operation width of an electron beam and a length of one chip. After acquiring the image, enter the threshold value to determine the defect,
The image of the portion determined to be defective is displayed. By repeating this, the optimum inspection condition is determined. This series of operations is called "small area trial inspection". Parameters such as thresholds and files set here are stored as parameters of the in-process file.

Various parameters required for inspection can be set by the above various inputs. However, in an actual semiconductor wafer, there are process variations within the wafer surface and between manufacturing lots, so it is not sufficient to set the image processing conditions in the small area trial inspection. It is necessary to decide the threshold.

Therefore, a final inspection is performed using the created recipe file (S13). That is, (1) stage constant speed continuous movement, position / height monitoring, (2) beam scanning, real-time correction (stage / Z sensor tracking), (3) secondary electron detection, AD conversion, image memory Input, (4) image processing, comparison judgment, (5) beam correction for every N stripes, and (6) defect number / defect position display.

The defect detection level and the erroneous detection level are confirmed from the monitor results (S14), and finally, if the conditions are appropriate, the various parameters input so far are registered in the product type file and the process file. (S15). Finally, the wafer is unloaded (S16).

Next, the inspection mode of the inspection apparatus of this embodiment will be described. FIG. 5 shows a processing flow of the inspection mode. Figure 2
When you select "Inspect" on the screen, the inspection mode starts.
First, the inspection conditions set in the recipe creation mode are input (S21). Next, the substrate to be inspected is loaded (S2
2) After performing alignment (S23) for measuring the arrangement of the substrate, calibration for confirming the detected light amount of the substrate is executed (S24), and stripe inspection is performed to acquire an image and extract a defect by image processing (S24). S25). next,
Check the defects extracted by the stripe inspection (S26),
The defect information and the confirmation result are output (S27), and the inspected substrate is unloaded (S28).

Next, the points improved by the present embodiment in the above "inspection" will be described. In conventional inspection equipment, when a recipe is applied to inspection of multiple wafers, the shelf number is specified using a screen different from the screen displaying the cassette shelf number.Therefore, the recipe is copied on the shelf number screen. I couldn't move. If the recipe was set incorrectly, the correction was complicated.

FIG. 6 is an initial screen of the "inspection" mode of this embodiment, in which the recipe name set for the shelf number 62 is displayed. The shelf number of the wafer to be inspected is specified on this screen, the recipe file is called, and the product type condition 65 is input. Also, the lot ID and wafer ID are input. Now, when the shelf number 62 is clicked, an arrow 64 for dragging appears, and the same recipe as the shelf number 62 is copied to the rack number 63 at the drag destination. Similarly, on the storage bin screen,
You can also move or delete recipes.

In the present embodiment, when the already prepared recipe is to be inspected for a plurality of wafers, the recipe can be copied, moved or deleted on the shelf number screen of the cassette containing the wafers. Since the user can visually confirm the movement of the recipe data, the operation is easy, and there is no fear that the recipe is erroneously set to a different storage bin.

Further, in this embodiment, the inspection result file by another inspection device can be used. FIG. 7 shows an example of an inspection result file by another inspection device. Most of the data such as the recipe name, die size, and die matrix include common data used in the inspection apparatus.

As described above, since the file (defect information file) generated (inspected) by another device is generated under the common rule, it is read to generate the recipe file for the own device. To do.

FIG. 8 shows a processing flow for reading a defect information file by another inspection device and making a recipe on the screen. A result file (defect information file) from another inspection device is read into the device by using a network or a recording medium (S30). The read file is analyzed with the tag name such as <die size> as a key as shown in FIG. 6 as a key. This is repeated for other tag names (S31).

Data read using the tag name as a key is converted for the device (S32). For example, unit conversion is performed. These data are the data in the recipe file, and are the wafer matrix information, the inspection area information, the alignment position information, and the like. The contents are displayed as wafer matrix information on the wafer display screen, or size data and the like are displayed on the screen (S3
3). The user confirms the content and then creates a new recipe for the inspection apparatus from the content (S3).
4).

As a result, the user can convert a defect information file from another for the apparatus and create a new recipe, so that it is not necessary to repeat the recipe creating work from the beginning as in the conventional case, and the recipe creating work can be performed. Can be shortened.

In the above inspection mode, if the position determined as a defect and the position to be compared (non-defective part) are alternately displayed, the difference between the defective part and the non-defective part may not be clear. In the present embodiment, only the defective portion is highlighted by alternately displaying the image of the defect and the image of the normal portion as a comparative reference at regular time intervals.

FIG. 9 shows the inspection result screen. The map display 55 displays the position of the defect, and the image display 56 displays the defect image at that position. An adjacent display unit 70 is provided in the inspection condition setting unit on this screen. As shown in the enlarged view of the adjacent display unit 70, the image names and display intervals of two adjacent images are set. As a result, the image display unit 5
The screens of the two images displayed in 6 are alternately switched, and only the defective portion appears to be emphasized due to the afterimage effect.

This image switching is performed by the storage means 4 in FIG.
5. The overall control 49 is used. In order to produce the afterimage effect, at least two images are automatically displayed at regular intervals. This not only makes the difference between the defective portion and the non-defective portion clear, but also reduces the complexity of user operation.

Here, the two images displayed alternately are
Although it is an image at the same position on different dies, it may be an image at the same position on the same die but with different acquisition times. As a result, the defect can be highlighted by a multifaceted display.

Another embodiment for making the defect image easy to see will be described. In this example, there is an operation screen for simultaneously displaying at least two images of a defect image and an image of a normal portion which is a comparison target on the same display device.

FIG. 10 shows an example of the inspection result screen. On the screen, it is possible to display the divided image 81 and change the display matrix 82. Further, a display page designation button 83, an image attribute display 84, a positive / negative inversion button 85 and the like are also displayed.

On this screen, the images displayed at the same time display attached data such as a defect number, a defect classification code, and coordinate data. In addition, the display image is not limited to the defect image, but includes an image acquired by another device. The matrix of images to be displayed can be changed by the user, and more images can be displayed by switching tabs by making one multi-screen display into one tab. The images displayed at the same time can be copied, moved, or deleted on the display screen.

With this, since the defect and the normal image can be simultaneously compared on the same screen, the defect can be easily determined and the operability can be improved. Not only the defect image but also a plurality of images of the same die, a plurality of images of a wafer, a plurality of images of other devices, etc. can be simultaneously displayed on the same screen for comparison.

Still another embodiment for displaying a defect image will be described. In the conventional inspection device, the stereoscopic effect of the defective portion cannot be displayed. In this embodiment, the stereoscopic display of the defective portion is realized.

FIG. 11 is an inspection screen having a stereo image display section. Two or more images of the defect are acquired by changing the image acquisition angle at which the electron beam irradiates the sample.
The stereoscopic view of the defect image is realized by setting the stereo display button section 93 to display 1 and 92 on the image display section 56 at the same time. By enabling stereoscopic viewing, it is possible to display defects in the depth direction that have not been found in conventional two-dimensional images.

The image obtained by changing the angle at which the sample is irradiated with the electron beam may be obtained by changing the angle of the electron beam or by tilting the table on which the sample is fixed. When changing the angle of electron beam irradiation, the position of the sample 9 is intentionally shifted from the beam irradiation center by moving the stages 31 and 32, and the beam is tilted by the beam deflection control (see FIG. 1). Get an image. By performing this operation while changing the angle, images with different beam angles are acquired. Further, the same result can be obtained by changing the inclination of the sample table on which the sample is fixed.

Next, the calibration method of this embodiment will be described. In the conventional inspection device, when determining the brightness of the image at the time of inspection, it is not clear visually what kind of correction was made to the brightness of the original image to change the brightness of the image. there were. Therefore, it is not possible to perform a consistent inspection because it is not known whether or not the brightness judged to be appropriate by the user is the same brightness correction made at the time of creating the recipe in the other steps.

FIG. 12 shows a calibration screen for determining the brightness of an image according to this embodiment. For the calibration, the signal from the secondary electron detector 20 is set to the control unit 5
This is performed by the screen operation unit 6 acquired via the. On this calibration screen, the brightness of the image in the inspection area of the wafer is determined. When the calibration 94 shown in the figure is selected, a "histogram" button 95 is displayed.

FIG. 13 is a histogram screen displayed when the histogram button 95 is pressed on the calibration screen. The brightness of the image in the inspection area of the wafer is displayed in a histogram. It has an operation area (slider operation) where you can change the brightness level and contrast level, and a text area that displays the current brightness and contrast. ing.

According to this, since the histogram of the brightness of the acquired image is displayed and the brightness for the histogram data is changed, what kind of correction was made to the brightness of the image at the time of the actual inspection. Can be visually recognized and the brightness can be consistently determined. Also, the user can arbitrarily set the brightness data. These settings are saved in the recipe file and will be used at the next inspection.
The calibration in this example is based on the “recipe creation” mode.

Next, an example of setting a specific area as a non-inspection area in setting the inspection area will be described. In many cases, defect information that does not want to be identified as a defect appears in the inspection result. Such defect information often occurs in a specific area within the die (or within the shot) depending on the manufacturing process.

In this embodiment, the defect maps are superposed using the defect coordinates, and the area where the defects overlap is designated as the specific area. That is, the image operation unit 6 calculates the specific area,
It is set in the control unit 5. Duplicate defect information is concentrated in a specific area within a die (or within a shot) and appears with similar properties, so that it can be determined.

FIG. 14 is a flowchart for designating the non-inspection area, and FIG. 15 is an explanatory diagram thereof. First, the defect maps are superposed by a die or a shot (S41), the overlapping defect group is enlarged (S42), and the region is designated as a non-inspection region (S43). Then, re-inspection is performed (S4
4), save the recipe including the designation of the non-inspection area (S4)
5).

As a result, it becomes possible for the user to set or change the inspection area so as to exclude in advance defect information that is not desired to be determined as a defect. Note that the present embodiment is also the case of the "recipe creation" mode.

FIG. 16 shows a method of designating a non-inspection area according to another embodiment. In this inspection, a classification code is determined for each defect type and applied to a specific defect, for example, a defect in which a pseudo signal is generated around the defect. Such a specific defect is applied to, for example, a defect that is not fatal to the user. Such a defect is a defect that the user does not have to detect.

First, a defect classification code is designated (S5
1) Search for defects of the designated classification (S5)
2). Next, the peripheral area of the designated defect is designated as the non-inspection region (S53). After that, re-inspection is performed and stored in the recipe. This embodiment is also the case of the "recipe making" mode.

FIG. 17 shows a processing flow in which the user directly sets coordinates, a defect area, and a defect size to set a non-inspection area around a defect that matches the conditions.

First, the defect image is filtered by area, size, coordinates, clusters or the like (S61), and the designated defect is searched (S62). Then, the peripheral area of the designated defect is designated as the non-inspection region (S6).
3). This embodiment is also the case of the "recipe making" mode.

For example, the brightness of the peripheral portion of the memory often changes depending on the conditions of the manufacturing process. This change in image brightness around the memory is often detected as a false alarm of a defect in a die comparison inspection for comparing the dies. According to the present embodiment, when the die area and the cell area (memory part) are inspected by the die comparison inspection, the periphery of the cell area is excluded from the inspection by the coordinate designation as shown in FIG. Therefore, the change in brightness around the cell area is not discriminated as a defect.
Such setting of the cell area can be applied not only to the “SEM” image but also to the “light microscope” image or the laser light image.

[0104]

According to the present invention, the chip inspection, the wafer sampling inspection and the like can be rapidly processed while observing the screen, so that defects over the entire product or defects in a specific area can be quickly detected. Further, it is possible to reliably detect the change in the process condition and feed it back to the process, and at the same time, feed it back to the adjustment of the man-hour difference and the payout budget.

By applying the inspection apparatus of the present invention to the board product process, it is possible to detect abnormalities in the product apparatus, conditions, etc. early and with high accuracy by referring to the screen. Abnormality countermeasure processing can be changed. As a result, the defect rate of the semiconductor device and other substrates can be reduced and the productivity can be improved.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a circuit pattern inspection apparatus according to an embodiment of the present invention.

FIG. 2 is a diagram illustrating a monitor unit.

FIG. 3 is a flowchart showing a recipe creating process according to an embodiment.

FIG. 4 is an explanatory diagram showing a recipe creation screen.

FIG. 5 is a process flow chart showing an inspection mode of one embodiment.

FIG. 6 is an explanatory diagram illustrating copying of a recipe on the initial screen of the inspection mode.

FIG. 7 is an explanatory diagram showing the contents of a result file of another device.

FIG. 8 is a process flow chart showing conversion of a recipe based on a result file of another device.

FIG. 9 is an explanatory diagram illustrating adjacent display of defect images.

FIG. 10 is an explanatory diagram illustrating simultaneous display of defect images.

FIG. 11 is an explanatory diagram illustrating stereoscopic display of a defect image.

FIG. 12 is an explanatory diagram for determining brightness at the time of inspection using a histogram.

FIG. 13 is an explanatory diagram of a histogram.

FIG. 14 is a processing flow chart of creating a new non-inspection region by using inspection result data.

FIG. 15 is an explanatory diagram of creating a new non-inspection region by using overlay.

FIG. 16 is a processing flow chart for creating a new non-inspection area using a classification code.

FIG. 17 is a process flow diagram of creating a new non-inspection region using a filter.

FIG. 18 is an explanatory diagram showing a non-inspection area around the cell area.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Circuit pattern inspection device, 2 ... Inspection room, 3 ... Electron optical system, 4 ... Optical microscope part, 5 ... Control part, 6 ... Image operation part,
7 ... Secondary electron detector, 8 ... Sample chamber, 9 ... Inspected substrate, 1
0 ... Electron gun, 11 ... Extraction electrode, 12 ... Condenser lens, 13 ... Blanking deflector, 14 ... Aperture, 15 ...
Scan deflector, 16 ... Objective lens, 17 ... Reflector, 18 ...
ExB deflector, 19 ... Primary electron beam, 20 ... Secondary electron detector, 21 ... Preamplifier, 22 ... AD converter, 23 ... Optical conversion means, 24 ... Optical transmission means, 25 ... Electrical conversion means, 26
... high-voltage power supply, 27 ... preamplifier drive power supply, 28 ... AD converter drive power supply, 29 ... reverse bias power supply, 30 ... sample stage,
31 ... X stage, 32 ... Y stage, 33 ... Rotation stage, 34 ... Position monitor length measuring device, 35 ... Inspected substrate height measuring device, 36 ... Retarding power supply, 40 ... White light source,
41 ... Optical lens, 42 ... CCD camera, 43 ... Scan signal generator, 44 ... Objective lens power supply, 45 ... Storage means, 4
6 ... Image processing circuit, 47 ... Defect data buffer, 49 ...
Overall control unit, 51 ... First image storage unit, 52 ... Second image storage unit, 53 ... Calculation unit, 54 ... Defect determination unit, 55 ... Map display unit, 56 ... Image display unit, 60 ... Mode switching unit, 61
... correction control circuit.

Front page continuation (51) Int.Cl. ⁷ Identification code FI theme code (reference) G06T 7/00 300 G06T 7/00 300F 5L096 H01J 37/22 502 H01J 37/22 502A 502D 37/28 37/28 B ( 72) Inventor Koichi Hayakawa 882 Ichige, Hitachi, Hitachinaka City, Ibaraki, Ltd.Hitachi High-Technologies Corporation Design and Manufacturing Headquarters, Naka Works (72) Inventor Takashi Hiroi 292 Yoshida-cho, Totsuka-ku, Yokohama, Kanagawa F-Term in Hitachi, Ltd., Production Technology Research Laboratory (reference) 2G001 AA03 BA07 CA03 FA02 FA06 GA06 HA07 HA09 HA12 HA13 HA20 JA02 JA03 JA12 JA13 JA20 KA03 LA11 MA05 PA11 PA12 2G051 AA51 AB02 AC21 CA04 EA12 EA14 FA01 4M106 AA01 BA02 BA20 BA18 CA21 DB43 5B057 AA03 BA02 CA12 CA16 DA03 DB02 DC33 5C033 UU06 5L096 BA03 GA08 HA07 JA03

Claims (8)

[Claims] 1. A irradiating means for irradiating the surface of a substrate on which a circuit pattern of a wafer is formed with light, a laser beam or a charged particle beam, a detecting means for detecting a signal generated from the substrate by the irradiating, and the detecting means. Storage means for converting the detected signal into an image and storing it, comparing means for comparing the stored image with an image formed from another identical circuit pattern, and determination for determining a defect on the circuit pattern from the comparison result In a circuit pattern inspection device equipped with means, when performing inspection on multiple wafers by a recipe that has already been created, on the screen showing the shelf number of the cassette containing wafers, from one shelf number to another shelf An apparatus for inspecting a circuit pattern, which is provided with a screen operation unit for copying, moving, or deleting a recipe for a serial number. 2. An irradiation means for irradiating the surface of the substrate on which the circuit pattern of the wafer is formed with light, a laser beam or a charged particle beam, a detection means for detecting a signal generated from the substrate by the irradiation, and the detection means. Storage means for converting the detected signal into an image and storing it, comparing means for comparing the stored image with an image formed from another identical circuit pattern, and determination for determining a defect on the circuit pattern from the comparison result In a circuit pattern inspection device equipped with a means, a recipe creation function that creates a recipe required to inspect a circuit pattern, including product type parameters and process parameters, and a defect information file inspected by another device are read and the wafer matrix is read. An image having a conversion function for converting information, inspection area information, and alignment position information for the inspection device. An operation unit, converted data is input to the recipe creation function testing apparatus for circuit pattern, characterized by creating a new recipe for the inspection apparatus. 3. An irradiation means for irradiating the surface of the substrate on which the circuit pattern of the wafer is formed with light, a laser beam or a charged particle beam, a detection means for detecting a signal generated from the substrate by the irradiation, and the detection means. Storage means for converting the detected signal into an image and storing it, comparing means for comparing the stored image with an image formed from another identical circuit pattern, and determination for determining a defect on the circuit pattern from the comparison result A circuit pattern inspecting device comprising a circuit pattern inspecting device for displaying a defect image and an image of a normal part to be compared and contrasted on the same display device. 4. The circuit pattern inspection apparatus according to claim 3, wherein the image of the defect and the image of the normal portion are alternately displayed at a predetermined time interval. 5. An irradiation unit that irradiates the substrate surface on which the circuit pattern of the wafer is formed with light, a laser beam, or a charged particle beam, a detection unit that detects a signal generated from the substrate by the irradiation, and the detection unit. Storage means for converting the detected signal into an image and storing it, comparing means for comparing the stored image with an image formed from another identical circuit pattern, and determination for determining a defect on the circuit pattern from the comparison result In a circuit pattern inspection device equipped with means, in order to change the angle of the image irradiated with the electron beam on the sample,
It has an angle changing means for changing the angle of the electron beam or the sample table, and an image display section for stereoscopically displaying a defect image by simultaneously displaying two or more images acquired by changing the angle on the same display device. A circuit pattern inspection device characterized by the above. 6. An irradiation means for irradiating a substrate surface on which a circuit pattern of a wafer is formed with light, a laser beam or a charged particle beam, a detection means for detecting a signal generated from the substrate by the irradiation, and the detection means. Storage means for converting the detected signal into an image and storing it, comparing means for comparing the stored image with an image formed from another identical circuit pattern, and determination for determining a defect on the circuit pattern from the comparison result In a circuit pattern inspection device including means, a screen operation unit that displays a histogram of the brightness of the acquired image and changes the brightness of the histogram data in order to determine the brightness of the image at the time of inspection is provided. A circuit pattern inspection device characterized in that 7. An irradiation means for irradiating a substrate surface on which a circuit pattern of a wafer is formed with light, a laser beam or a charged particle beam, a detection means for detecting a signal generated from the substrate by the irradiation, and the detection means. Storage means for converting the detected signal into an image and storing it, comparing means for comparing the stored image with an image formed from another identical circuit pattern, and determination for determining a defect on the circuit pattern from the comparison result In a circuit pattern inspection device having a screen configuration including means, a screen operation unit is provided that superimposes inspection results on each die or each shot and designates an overlapping area from the defect distribution as an inspection unnecessary area. Characteristic circuit pattern inspection device. 8. An irradiation means for irradiating a substrate surface on which a circuit pattern of a wafer is formed with light, a laser beam or a charged particle beam, a detection means for detecting a signal generated from the substrate by the irradiation, and the detection means. Storage means for converting the detected signal into an image and storing it, comparing means for comparing the stored image with an image formed from another identical circuit pattern, and determination for determining a defect on the circuit pattern from the comparison result In a circuit pattern inspection device having means, when a die area and a cell area are inspected by a die comparison inspection, a screen operation unit for excluding the periphery of the cell area as an inspection unnecessary area is characterized. Circuit pattern inspection device.