JPH0260A - Method and device for ion beam processing - Google Patents

Abstract

PURPOSE:To execute the correction processing of fine circuit patterns by irradiating the work with ion beams as a wide scanning area, measuring secondary charge control particles, detecting the correction point, scanning said point as a narrow scanning area and correcting the same. CONSTITUTION:The high brightness ion beams 78 are drawn out of a liquid metal ion source 75 and are focused by electrostatic lenses 80-82. The spot 78' of the focusing ion beam 78 is scanned by deflecting electrodes 84, 85 over a wide scanning area. The secondary charge particles generated from a sample 74 having the fine circuit patterns are detected by a secondary charge particle detector 95 and the correction point is detected by the magnified SIM image obtd. by an SIM observing device 96. The scanning region of the focusing ion beam 78 is then limited by the deflecting electrodes 84, 85 and the defective position of the patterns is irradiated with the ion beam 78, by which the defect is corrected. The inspection is made by using the secondary electron image or secondary ion image formed by scanning of the ion beam 78 and the detect is corrected by the microion beam in such a manner, by which the defect of <=0.5mu patterns is inspected, removed and corrected.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an ion beam processing method and apparatus for modifying a workpiece having a fine circuit pattern of 1.5 μm or less, such as a mask, using an ion beam. .

[Conventional technology]

In recent years, semiconductor integrated circuits (ICs) have become significantly smaller and more highly integrated, and the wiring pattern size is shifting from 3μ to 2μ, and it is predicted that 1 to 1.5μ patterns will be realized in a few years. There is.

FIG. 1(a) shows a cross section of the photomask.

The photomask shown in this figure consists of a thin film (thickness of several hundred nanometers) made of a material with low transmittance to exposure light, such as a metal material such as chromium or a metal compound material such as iron oxide, on a glass substrate 1. ~several thousand people) are deposited and formed into a desired pattern 2 by photo-etching technology. Here, dimension A is the interval between patterns, and dimension B is the width of the patterns.

FIG. 1(b) shows a cross section of an X-ray exposure mask used for forming even finer wiring patterns.

The mask shown in this figure is supported by a support substrate 3 made of Si and is made of Parylene 4 with a thickness of several microns, and is made of Cr with a thickness of about 200 μm.
It has a thin film 5 on which A with high absorption for X-rays is formed.
A pattern is formed by several thousand U6 films. Approximately 1000 Cr thick on top of A u 6
7 is formed by a lift-off method so as to serve as a mask when etching Au6 to form a pattern.

FIG. 2 is a top view of a portion of these masks.

In the mask shown in this figure, a wiring pattern 9 is formed on a glass substrate 8, and this wiring pattern 9 is formed of, for example, a thin film of metal Cr. Such a mask has a defect designated by the symbol 10.11°12.
This usually occurs during the pattern forming process. this is,
This is mainly due to the presence of foreign matter in the photoetching process. The symbol 10°11 is called a black spot defect, and metal Cr exists in a place where it should not exist originally. Reference numeral 12 is called a white spot defect, in which metal Cr is missing where it should originally exist. If a photomask with such a defect is used as is, the defect will be directly transferred to the element pattern on the wafer, resulting in a defective IC. Among the two types of defects, black spot defects are more numerous.

FIG. 3 shows a conventional example of the mask defect inspection apparatus as described above, and FIG. 4 shows the function of the binarization circuit of the apparatus.

In the apparatus shown in FIG. 3, a mask 13 to be inspected is fixed on an XY child table 4. In the apparatus shown in FIG.

The light emitted from the light source 15 is guided by an optical fiber 16 and illuminates the mask 13 from below. Under this transmitted light illumination, the objective lens 17 forms an image of the mask pattern through the optical elements 1g and 19.20 onto the linear image sensor 21 in which minute photoelectric conversion elements are arranged in a row.

The output of this linear image sensor 2I is input to a 2M other circuit 23 and binarized. That is, Fig. 4(a)
The output of the linear image sensor 21 is replaced with a digital signal consisting of 0 level and level, as shown in FIG. 4(b), depending on whether it is higher or lower than an arbitrarily set output level h. This means that the electrical output from the linear image sensor 21 that captures the mask pattern image is
Optical.

This is to improve the poor SZN ratio due to electrical and other factors.

The XY child table 4 is moved perpendicular to the direction in which the linear image sensors 21 are arranged by a drive motor controlled by a control device. Therefore, the output from the binarization circuit 23 scans the image of the mask pattern two-dimensionally.

On the other hand, the accurate original pattern information stored on the magnetic tape 24 is stored on the magnetic disk 24, which can be read at high speed.
Saved in The position of the XY child table 4 is read every moment by linear encoders 26 and 27, and the information of the original pattern from the magnetic disk 25 at the corresponding location and the 2
Comparison with the digitization circuit output is performed in the comparison circuit 28.

In this way, a pattern different from the original pattern, that is, the position of the defect, is recorded on the cassette tape 30 by the defect position wiring circuit 29.

FIG. 5 shows a conventional example of a device for correcting mask defects found as described above using a laser.

In this device, a laser beam 32 emitted from a laser oscillator 31 is reflected by a reflection mirror 33, passes through a semi-transparent mirror 34 through an aperture (rectangular opening) 47, is focused by a lens 35, and is focused on a fine movement stage 36. The defect 38 of the mask 37 placed on the mask 37 is irradiated and removed.

Under repair, half mirror 39, lighting lamp 40. Concave mirror 41. An illumination optical system consisting of a condenser lens 42 illuminates the surface of the mask 37, which is a sample.

Here, regarding the positioning of the defect, the defect position is determined by the movement control device 46 of the stage 36 based on the information from the cassette tape 45 on which the defect position information is recorded by the defect inspection device shown in FIG. This is done by moving the stage 36 on which the mask is placed so that it is within the field of view of the lenses 43 and 44, and then slightly moving the stage 36 while observing.

[Problem to be solved by the invention]

The conventional techniques related to mask defect inspection and correction described above have the following drawbacks. That is, (1) since defects are inspected by an optical method, it is impossible to obtain a resolution below the diffraction limit of light, and the practical resolution is considered to be approximately 0.65μ. Therefore, defects of 0.5 μm or less in fine patterns such as VLSI cannot be inspected.

(2) Since defects are removed and corrected using a laser device, it is difficult to remove and correct defects with an accuracy below the focusing limit of the laser beam. Since the practical removal correction accuracy is considered to be limited to 0.5μ, it is not suitable for correction of VLSI fine patterns of 1.5μ or less.

(3) Since defect inspection and correction are performed using separate devices, the device becomes expensive and the number of man-hours increases. In particular, since position detection and positioning are repeated, the mechanism and process of this part are redundant, which is wasteful.

The purpose of the present invention is to eliminate the drawbacks of the prior art as described above, and to reduce the
An object of the present invention is to provide an ion beam processing method and an apparatus for the same, which allow correction processing to be performed with a resolution of less than μ.

[Means to solve the problem]

That is, in order to achieve the above object, the present invention extracts a high-intensity ion beam from a high-intensity ion source, focuses it with an electrostatic lens, and scans the focused ion beam with a deflection electrode over a wide scanning area to form a fine circuit. A detector detects secondary charged particles generated from a patterned workpiece and enlarges the SIM.
Obtain an image, detect the correction area, scan the focused ion beam to the correction area using a deflection electrode in a narrow scanning area, and use the blanking electrode to irradiate and stop the ion beam on the workpiece. This is an ion beam processing method characterized by performing the following steps.

Further, the present invention provides a high-intensity ion source, an extraction electrode for extracting a high-intensity ion beam from the high-intensity ion source, an electrostatic lens for focusing the high-intensity ion beam extracted from the extraction electrode, and the electrostatic lens. A deflection electrode that deflects the focused ion beam, a blanking electrode that stops the ion beam from irradiating a workpiece with a fine circuit pattern, and detects secondary charged particles generated from the workpiece. a secondary charged particle detector that displays a SIM image obtained from the secondary charged particle detector; a display means that displays a SIM image obtained from the secondary charged particle detector; The ion beam processing apparatus is characterized by comprising a control means for controlling a narrow scanning area when processing a part.

C Effect] With the above-described configuration, it is possible to detect a correction point without damaging the workpiece, and it is possible to accurately perform fine correction work on a fine circuit pattern.

〔Example〕

Hereinafter, the present invention will be explained based on the drawings.

FIG. 6 shows an example of a mask defect inspection/correction apparatus for carrying out the method of the present invention.

In FIG. 6, counterintelligence measures are taken on the pedestal 47 by an air servo 48, and a vacuum container 49 is installed on the pedestal 47.

A sample chamber 50 is provided in the lower half of the vacuum container 49, and a sample exchange chamber 51 is provided on the side thereof.

The upper half of the vacuum container 49 and the sample chamber 501J are partitioned off by a gate valve 52, and the sample chamber 50 and the sample exchange chamber 51 are partitioned off by another gate valve 53. Also.

A vacuum evacuation means is connected to the vacuum container 49.

The evacuation means includes a vacuum pipe 54 connected to the upper half of the vacuum container 49, the sample chamber 50, and the sample exchange chamber 51.
55.56. Oil rotary pump 57. Oil trap 58. Ion pump59. It has a turbo-molecular pump 60 and valves 61, 62, 63, 64, and connects the inside of the vacuum container 49, the sample chamber 50, and the sample exchange chamber 51 to 10-'
t.

It can be evacuated to a vacuum below rr.

A stage 65 is installed in the sample chamber 50 on the pedestal 47, a sample stage 70 is placed on the stage 65, and a sample 74, which is a mask, is placed on top of the stage 65. ing. Further, a drawer 70' is attached to the sample stage 70.

The document table 65 is connected to an X-direction drive motor 66, a Y-direction drive motor 67, a Z-direction fine movement micrometer 68, and a θ-direction (rotation) movement ring from the outside of the sample chamber 50 via rotation introduction terminals 71, 72, and 73. 69, X.

It is configured to be able to move in the Y direction and finely adjust the rotation angle in two directions and in the horizontal plane. Said X.

The YI movement motors 66, 67, the Z-direction fine movement micrometer 68, and the θ-direction movement ring 69 are connected to and controlled by the control device 103.

Inside the vacuum container 49, a liquid metal ion source 75, which is a high-brightness ion source, a control (bias) electrode 76, and an extraction electrode 77 for the ion beam 78 are arranged in order from above toward the stage 65. , an aperture (circular opening) 79, an aperture with a micrometer (rectangular opening) 106, an electrostatic lens 80.81° 82, a blanking electrode 83, an aperture 9', and a deflection electrode 84 in the X and Y directions. 85 and a secondary charged particle detector 95 are provided.

The filament of the liquid gold scrap ion source 75 is connected to a power source 86.
and is heated by the power source 86.

The controller electrode 76 is connected to a power source 87 and applies a low positive and negative voltage near the tip of the tip provided on the filament of the liquid metal ion source 75 to control the current.

The extraction electrode 77 is connected to a power source 88, and after heating the filament of the liquid metal ion source 75 by passing a current through it, the extraction electrode 77 is connected to the power source 88 in a vacuum of 10-' torr or less.
When a negative voltage of several kilovolts to several tens of kilovolts is applied to the extraction electrode 77 by 8, the ion beam 78 is extracted from the tip of the tip provided on the filament.

The aperture 9 receives the extracted ion beam 78.
Take out the center part.

The electrostatic lenses 80.81 are connected to a power source 89.90, and these electrostatic lenses 80.81 and an electrostatic lens 83 installed below the ion beam 78 extracted by the aperture 9. is focused on a fine area of 0.5 μφ or less.

The blanking electrode 83 is connected to a power source 92, scans the ion beam 78 at a very high speed, removes it from the outside of the aperture 9', and stops irradiating the sample 74 with the ion beam at a high speed.

The deflection electrodes 84.85 are connected to the power supply 93 and deflect the ion beam 78 focused by the electrostatic lens 80.81.82 in the X and Y directions to form a spot 7 on the surface of the sample 74.
Tie 8'.

The secondary charged particle detector 95 is arranged in the sample chamber 50 and detects secondary electrons or secondary charged particles generated from the material 74 when the material 74 is irradiated with the ion beam 78.
It stops receiving the next ions, converts the intensity into an electric current, and sends the output to the SIM@detection device 96.

Power supply 86 for the filament of the liquid metal ion source 75
The power supply 87 for the control electrode, the power supply 88 for the extraction electrode, and the power supply 89.90 for the electrostatic lens are expressed by the number 10.
It is connected to the high voltage power supply 91 of the KV. Also.

The power supply 92 for the blanking electrode and the power supply 93 for the deflection electrode are connected to a control device 94 to scan the ion beam 78 according to a fixed pattern 7.

The power source 93 for the deflection electrode and the secondary charged particle detector 95 are connected to a SIMli%% device 96. This S
The IMI detection device 96 receives a signal regarding the amount of deflection of the ion beam 78 in the X and Y directions from the power supply 93 for the deflection electrode, scans the bright spot on the cathode ray tube 97 in synchronization with the signal, and measures the brightness of the bright spot. By changing the intensity of the current from the secondary charged particle detector 95, an image of the sample corresponding to the secondary electron emission ability at each point of the sample 74 is obtained.
I M (5cann)ngI on Micro
It is configured to be able to magnify the sample surface by 1 m using the function of a scope (scanning ion microscope), and the information is sent to an inspection device for the sample 74.

The inspection device for the sample 74 includes a memory cop 98, a comparison circuit 99, and a magnetic disk 100. The memory scope 98 also records an image of the SIMwi detection device 96 based on the signal from the secondary charged particle detector 95. Original pattern information is stored on the magnetic disk 100 via a magnetic tape 101.

The comparison circuit 99 is connected to the control device 10 of the stage 65.
Based on the image position information from 3, the image of the pattern of the sample 74 at the position corresponding to the information is retrieved from the memory scope 98, the information of the original pattern is retrieved from the magnetic disk 100, and both patterns are compared. When they do not match, it is determined that there is a defect.

A control system 102 is connected to the inspection device for the sample 74,
The high voltage power supply 91 and the control device 94 are connected to the control system 102 . The control system 102 connects the power source connected to the high voltage power source 91 and the control device 94 to the sample 74.
During inspection and defect inspection, the ion beam extraction conditions are switched to a small current, low accelerating voltage, and a wide scanning area, and after detecting a defect in the pattern of the sample 74, a large current and high accelerating voltage are used when removing and correcting the defect.

It is configured to be able to switch and control the ion extraction conditions in a narrow scanning range.

Note that 104 and 105 in FIG. 6 correspond to the linear encoders 26 and 27 in FIG. 3, respectively.

Next, the method of the present invention will be explained in relation to the operation of the mask defect inspection/correction apparatus of the above embodiment.

Before introducing the sample 74 into the sample chamber 50, the entire vacuum container 49 is evacuated by the vacuum evacuation means.

Next, the sample stand 70 is pulled out to the sample exchange chamber 51 via the drawer 70' attached to the sample stand 70, the gate valve 53 is closed, the door of the sample exchange chamber 51 is opened, and the sample stand 70 is pulled out.
A sample 74 as a mask is placed on top of the sample exchange chamber 51.
After preliminary evacuation of the
The sample stage 70 is placed in a fixed position, and the X and Y direction drive motors 66 and 67 are operated by the control device 103.
5 to the inspection start position of the sample 74, and further move the Z-direction fine movement micrometer 68 and the θ-direction movement ring 69.
to finely adjust the rotation angle with respect to the Z direction and the horizontal plane.

Next, the control system 102 switches the high voltage electrode 91 and the control device 94, and each electrode 86 to 90, 92, 93 is used to extract an ion beam with a small current, low accelerating voltage, and a wide scanning area suitable for observing the sample 74 and inspecting defects. After setting the conditions, the sample 74 is observed and inspected for defects.

Then, a current is supplied to the filament of the liquid metal ion source 75 by the power source 86 to heat it to 10'-St.

In a vacuum below rr, the extraction electrode 77 is connected by the power source 88.
When a negative voltage of several kilovolts to several tens of kilovolts is applied to the liquid metal ion source 75, an ion beam 78 is extracted from an extremely narrow region at the tip of the tip provided on the filament of the liquid metal ion source 75. When extracting the ion beam 78, a low positive and negative voltage is applied from the control electrode 76 to the vicinity of the tip of the filament of the liquid metal ion source 75 through the power source 87 to control the current.

The ion beam 78 extracted from the liquid metal ion source 75 has only its central portion taken out by the aperture 9, and is further connected to an electrostatic lens 80.81 and other electrostatic lenses to which a voltage is applied through a power source 89.90. 82, the deflection electrode 8 is focused to a spot 78' having a size of 0.5 μφ or less, and is operated by applying a voltage from a power source 93.
4.85 in the X and Y directions, a spot 78' is formed on the surface of the sample 74, and the surface of the sample 74 is irradiated with the ion beam 78.

As described above, when the surface of the sample 74 is irradiated with the ion beam 78, secondary charged particles are generated from the sample 74. These secondary charged particles, such as secondary electrons or secondary ions, are stopped by a secondary charged particle detector 95, and their intensity is converted into an electric current and sent to a SIM detection device 96.

Further, the SIM observation device 96 receives a signal regarding the amount of deflection of the ion beam 78 in the x and Y directions from the power source 93 for the deflection electrode, and in synchronization with this, scans the bright spot on the cathode ray tube 97 and increases the brightness of the bright spot. By changing the current intensity according to the current intensity from the secondary charged particle detector 95, images of the sample 74 are obtained at each point, and the sample surface is observed under magnification.

Next, the image of the sample 74 obtained by the SIM 11 inspection device 96 is recorded in the memory scope 98 of the sample 74 inspection device.

Next, in the comparison circuit 99 of the inspection device for the sample 74.

The image of the sample 74 is taken out from the memory scope 98, and based on the image position information from the control device 103 of the drive system of the stage 65, the image of the sample 74 is extracted from the original pattern information stored in the magnetic disk 100. Information on the pattern at the corresponding position is extracted, the image of the sample 74 and the information on the original pattern are compared, and when the two do not match, it is determined that there is a defect.

In this way, defects in patterns of 0.5 μι or less can be inspected by using the secondary electron image or secondary ion image obtained by scanning the ion beam 78 with a diameter of 0.5 μι or less.

After one observation and inspection of the sample 74, the blanking electrode 83 is activated to scan the ion beam 78 at an extremely high speed, and is removed to the outside of the aperture 9' to stop the irradiation of the ion beam 78 onto the sample 74 at high speed. let

The sample 74 is detected by the comparison circuit 99 of the inspection device for the sample 74.
When a defect is detected in the pattern, the control system 102 is switched to the extraction conditions for the ion beam 78 of large current, high acceleration voltage, and narrow scanning area suitable for correction, and the large current ion beam is removed from the liquid gold scrap ion source 75. 78 is taken out, a high acceleration voltage is applied by the control electrode 76, the ion beam 78 is focused on a spot of 0.5 μφ or less by the electrostatic lens 80, 81, 82, and the scanning range is limited by the deflection electrode 84, 85, and the pattern is The defect position is irradiated with an ion beam 78, and the defect is corrected by sputtering removal. Alternatively, the ion beam 78 may be imaged and projected onto the defect position to remove it by sputtering.

In this way, by performing correction using a micro ion beam, it is possible to remove and repair even minute defects of 0.5 μm or less.

After correcting the defect in the pattern of the sample 74, the control system is again switched to a value suitable for w4 detection and inspection of the sample 74, and the above-described operations can be repeated to inspect the corrected sample 74.

After completely correcting the defect in the pattern of the sample 74, each power supply is stopped, the gate valve 52 between the upper half of the vacuum container 49 and the sample chamber 50 is closed, the other gate valve 53 is opened, and the pull-out tool is closed. The sample stage 74 is pulled out to the sample exchange chamber 51 via 70', and the mask, which is the corrected product, is taken out.

Note that in the present invention, a dividing resistor may be used instead of the high voltage power supply 91.

In addition, a binarization circuit is connected to the secondary charged particle detector 95,
Depending on whether the signal is higher or lower than the reference level, it may be converted into a binary signal of 0 level and level, and then sent to the SIM detection device.

〔Effect of the invention〕

As explained above, according to the present invention, an ion beam from a high-intensity ion source is focused and scanned on a fine area of 0.5 μφ or less using a charged particle optical system, and the spot of the ion beam is formed into a fine circuit pattern. irradiate and measure the intensity of the secondary charge control particles to detect the correction area in a wide scanning area, and when making corrections in the narrow scanning area. This has the effect of allowing correction work to be performed with high resolution.

[Brief explanation of the drawing]

FIGS. 1(a) and (b) are cross-sectional views showing an example of a mask to be used in the present invention, FIG. 2 is a plan view thereof, and FIG. 3 is a diagram showing a conventional example of a mask defect inspection device. Figure 4 (a), (b)
) is a functional explanatory diagram of the binarization circuit in the inspection device, FIG. 5 is a diagram showing a conventional example of a mask defect device, and FIG. 6 is a system diagram showing an example of a device implementing the method of the present invention. . 10, 11.12... Defect in wiring pattern of mask. 47... Frame, 49... Vacuum container,
50... Sample chamber, 51... Sample exchange chamber, 54-64... Members constituting vacuum evacuation means, 65
... Loading table, 66, 67... X and Y direction knocking motor, 68... Z
Directional fine movement micrometer, 69...θ direction movement ring, 70... Sample stage, 71-73... Rotation introduction terminal,
74... Sample which is a mask, 75... Liquid metal ion source which is a high brightness ion source, 76... Control electrode, 77... Ion beam extraction electrode, 78... Ion beam, 78' ...Ion beam spot. 79, 79'...Aperture, 80-83...Electrostatic lens, 84...Blanking electrode, 84.85...
・Deflection electrode, 86-90...power supply, 91・
...High voltage power supply, 92, 93...Power supply, 94...Control device for power supply of blanking electrode and deflection electrode, 95...Secondary charged particle detector, 96...SIN@ detection device, 98 ...Memory Scope. 99... Comparison circuit for the image of the sample pattern and information on the original pattern, 100... Magnetic disk for storing information on the original pattern, 102... Power supply during observation/inspection and defect correction. A control system for switching operating conditions, 103... A control device for the drive system of the stage. Tow figure (α) (b) Fig.

Claims (1)

[Claims] 1. Extracting a high-intensity ion beam from a high-intensity ion source,
The ion beam is focused by an electrostatic lens, and the focused ion beam is scanned over a wide scanning area by a deflection electrode. Secondary charged particles generated from a workpiece having a fine circuit pattern are detected by a detector and an enlarged SIM image is created. Then, the focused ion beam is scanned and corrected using a deflection electrode to cover the correction area in a narrow scanning area, and the blanking electrode is used to irradiate and stop the ion beam on the workpiece. An ion beam processing method characterized by: 2. A high-intensity ion source, an extraction electrode that extracts a high-intensity ion beam from the high-intensity ion source, an electrostatic lens that focuses the high-intensity ion beam extracted from the extraction electrode, and an electrostatic lens that focuses the high-intensity ion beam extracted from the extraction electrode. A deflection electrode that deflects the focused ion beam, a blanking electrode that stops the ion beam from irradiating a workpiece having a fine circuit pattern, and a secondary electrode that detects secondary charged particles generated from the workpiece. a charged particle detector; a display means for displaying a SIM image obtained from the secondary charged particle detector; An ion beam processing device characterized by comprising: control means for controlling a narrow scanning area when processing the ion beam.