JPH0429052B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an ion beam processing apparatus for modifying a workpiece, such as a mask, having a particularly fine circuit pattern of 1.5 μm or less 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 dimensions are moving from 3μ to 2μ, and it is predicted that 1 to 1.5μ patterns will be realized in a few years. .

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

The photomask shown in this figure consists of a thin film (with a thickness of several hundred to A desired pattern 2 is formed by photo-etching. Here, dimension A is the interval between patterns, and dimension B is the width of the patterns.

FIG. 1b 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 Si supporting substrate 3 and is placed on a parylene 4 with a thickness of several microns and has a thickness of 200 Å.
A pattern is formed on the Cr thin film 5 of about 100 Å in thickness, with a thickness of several 1000 Å made of Au6, which has a high absorption of X-rays. Approximately 1000 thick on top of Au6
Cr7 of Å was formed by lift-off method 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 the symbol 10,1
Defects indicated by 1 and 12 usually occur during the pattern forming process. This is mainly due to the presence of foreign matter in the photoetching process. Symbols 10 and 11 are called black spot defects, and metal Cr exists in places where it should not originally exist. 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 defects is used as is, these defects will be directly transferred to the element patterns on the wafer, resulting in defective ICs. 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, the mask 13 to be inspected is fixed on an XY table 14. The light emitted from the light source 15 is transmitted through the optical fiber 1
6, the mask 13 is irradiated from below. Under this transmitted light illumination, the objective lens 17 transfers the image of the mask pattern to the optical elements 18, 19, 20.
The image is then formed onto a linear image sensor 21 in which minute photoelectric conversion elements are arranged in a row.

The output of this linear image sensor 21 is input to a binarization circuit 23 and binarized. That is, the output of the linear image sensor 21 as shown in Fig. 4a is converted into a digital signal consisting of 0 level and 1 level as shown in Fig. 4b, depending on whether it is higher or lower than an arbitrarily set output level h. Replace. This is because the electrical output from the linear image sensor 21 that captures the mask pattern image is affected by optical, electrical, and other factors.
This is to improve the deterioration of the S/N ratio.

The XY table 14 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, accurate original pattern information stored on the magnetic tape 24 is temporarily stored on a magnetic disk 25 that can be read at high speed. XY table 14
The position of is read every moment by linear encoders 26 and 27, and a comparison circuit 28 compares the original pattern information from the magnetic disk 25 at the corresponding location with the output of the binarization circuit.

In this way, a pattern different from the original pattern, that is, the defect position is changed to the defect location wiring circuit 2.
9 is recorded on the cassette tape 30.

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,
After passing through the semi-transparent mirror 34 through the aperture (rectangular opening) 47, the light is focused by the lens 35,
The defect 38 of the mask 37 placed on the fine movement stage 36 is irradiated and removed.

Under modification, half mirror 39, lighting lamp 40,
An illumination optical system consisting of a concave mirror 41 and 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 drive 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. so as to enter the field of view of the eyepieces 43 and 44,
After the stage 36 on which the mask is placed moves, the stage 36 is moved slightly while being observed.

[Problem to be solved by the invention]

The conventional techniques related to mask defect inspection and correction described above have the following drawbacks. In other words, (1) Since defect inspection is performed using an optical method, it is impossible to obtain a resolution below the diffraction limit of light, and the practical resolution is approximately 0.5μ.
is considered to be the limit. Therefore, VLSI
It is not possible to inspect defects smaller than 0.5μ in fine patterns such as

(2) Since defect removal and correction is performed using a laser device, it is difficult to perform removal and correction with an accuracy below the focusing limit of the laser beam. Practical removal correction accuracy is considered to be at the limit of 0.5μ, so 1.5μ
It is not suitable for modifying the following VLSI fine patterns.

(3) Since defect inspection and correction are performed using separate equipment, the equipment 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.

In order to solve the above-mentioned problems of the prior art, an object of the present invention is to provide an ion beam capable of performing fine processing of 0.5 μm or less with a resolution of 0.5 μm or less on a workpiece having a fine circuit pattern. Our goal is to provide processing equipment.

[Means to solve the problem]

That is, in order to achieve the above object, the present invention has the following features:
A high-brightness ion source, an extraction electrode for extracting a high-brightness ion beam from the high-brightness ion source, and a spot of 0.5 μm or less for the high-brightness ion beam extracted from the extraction electrode on a workpiece having a fine circuit pattern. an electrostatic lens that focuses the focused ion beam, a deflection electrode that deflects the focused ion beam that is focused by the electrostatic lens, and a blanking member that controls and stops the irradiation of the high-intensity ion beam to the workpiece having the fine circuit pattern. By the electrode and the above electrostatic lens
a secondary charged particle detector that detects secondary charged particles generated from the workpiece having the fine circuit pattern using an ion beam spot focused to 0.5 μm or less and scanned by a deflection electrode; an observation means for forming and observing a SIM image of a repaired part on a workpiece based on a secondary charged particle signal obtained from a device; and a control means for controlling the deflection electrode in order to change the scanning area of the ion beam spot of 0.5 μm or less when processing by irradiating the ion beam spot of 0.5 μm or less to the repaired area. This is an ion beam processing device characterized by the following.

[Effect]

With the above 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, the pedestal 47 is provided with anti-seismic measures using 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 50 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. Further, the vacuum container 49 is connected to a vacuum evacuation means.

The evacuation means includes vacuum pipes 54, 55, 56 connected to the upper half of the vacuum container 49, the sample chamber 50, and the sample exchange chamber 51, an oil rotary pump 57, an oil trap 58, and an ion pump 5.
9, turbo molecular pump 60 and valves 61, 6
2, 63, and 64, so that the inside of the vacuum container 49, the sample chamber 50, and the sample exchange chamber 51 can be evacuated to a vacuum of 10 ^-5 torr or less.

In the sample chamber 50 on the pedestal 47, there is a stage 65.
is installed, a sample stand 70 is placed on the stage 65, and a sample 74 serving as a mask is placed on top of the sample stand 70. Further, the sample stage 70 is provided with a drawer 70'.

The document stand 65 has rotation introduction terminals 71, 72,
73 from the outside of the sample chamber 50 by 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 69. It is configured to allow fine adjustment of the rotation angle within. the X, Y drive motors 66, 67;
The Z-direction fine movement micrometer 68 and the θ-direction moving 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 an ion beam 78 are arranged in order from above toward the stage 65. , an aperture (circular opening) 79 and an aperture with a micrometer (rectangular opening) 106
, electrostatic lenses 80, 81, 82, blanking electrode 83, aperture 79', deflection electrodes 84, 85 in the X and Y directions, and secondary charged particle detector 9.
5 is provided.

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

The controller electrode 76 is connected to a power source 87 and controls the current by applying a low positive and negative voltage near the tip of the chip provided in the filament of the liquid metal ion source 75.

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 heated with several KV by the power source 88 in a vacuum of 10 ^-5 torr or less.
When a negative voltage of up to several tens of kilovolts is applied, an ion beam 78 is extracted from the tip of the chip provided on the filament.

The aperture 79 extracts the central portion of the extracted ion beam 78.

The electrostatic lenses 80 and 81 are powered by power sources 89 and 90.
The ion beam 7 extracted by the aperture 79 is connected to the electrostatic lenses 80 and 81 and the electrostatic lens 83 installed below.
8 into a minute area of 0.5μφ or less.

The blanking electrode 83 is connected to a power source 92 and scans the ion beam 78 at a very high speed to remove the ion beam 78 to the outside of the aperture 79'.
The ion beam irradiation is stopped at high speed.

The deflection electrodes 84 and 85 are connected to a power source 93 and deflect the ion beam 78 focused by the electrostatic lenses 80, 81, and 82 in the X and Y directions.
A spot 78' is connected to the surface of 4.

The secondary charged particle detector 95 is arranged in the sample chamber 50 and receives secondary electrons or secondary ions, which are secondary charged particles, generated from the material 74 when the material 74 is irradiated with the ion beam 78, The intensity is converted into electric current, and the output is converted into SIM observation device 9.
6 is scheduled to be sent.

A power source 86 for the filament of the liquid metal ion source 75, a power source 87 for the control electrode, a power source 88 for the extraction electrode, and a power source 8 for the electrostatic lens.
9 and 90 are connected to a high voltage power source 91 of several tens of kilovolts. Further, the power supply 92 for the blanking electrode and the power supply 93 for the deflection electrode are connected to a control device 94.
The ion beam 78 is connected to the ion beam 78 to scan the ion beam 78 according to a certain pattern.

The power source 93 for the deflection electrode and the secondary charged particle detector 95 are connected to a SIM observation device 96. This SIM observation device 96 receives a signal regarding the amount of deflection of the ion beam 78 in the X and Y directions from a power source 93 for the deflection electrode, scans a bright spot on a cathode ray tube 97 in synchronization with the signal, and scans the bright spot of the cathode ray tube 97. By changing the brightness and the current intensity 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.
It is configured to enable magnified observation of the sample surface using the SIM (Scanning Ion Microscope) function, and the information is transmitted to the sample 74.
It is designed to be sent to the inspection equipment of

The inspection device for the sample 74 is a memory cop 98.
, a comparison circuit 99 , and a magnetic disk 100 . The memory scope 98 is a SIM observation device 96 based on signals from the secondary charged particle detector 95.
Record the images together. The magnetic disk 10
Information on the original pattern is stored in 0 through the magnetic tape 101. Based on the image position information from the control device 103 of the stage 65, the comparison circuit 99 extracts the image of the pattern of the sample 74 at the position corresponding to the information from the memory scope 98, and extracts the information of the original pattern. magnetic disk 10
The pattern is drawn from 0 and compared, and when the patterns do not match, it is determined that there is a defect.

A control system 102 is connected to the testing device for the sample 74, and the high voltage power supply 91 and the control device 94 are connected to the control system 102. The control system 102 switches the power supply connected to the high-voltage power supply 91 and the control device 94 to the ion beam extraction conditions of low current, low accelerating voltage, and wide scanning range during observation and defect inspection of the sample 74. After detecting a pattern defect, when removing or correcting the defect, the ion extraction conditions can be switched to large current, high accelerating voltage, and narrow scanning area.

In addition, 104 and 105 in Fig. 6 are the third
This corresponds to the linear encoders 26 and 27 in the figure.

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 drawer 7 attached to the sample stage 70
0' to the sample exchange chamber 51, close the gate valve 53, and close the sample exchange chamber 51.
Open the door and place the sample 7, which is a mask, on the sample stage 70.
4, pre-evacuate the sample exchange chamber 51, place the sample in the sample chamber 50, place the sample table 70 at the fixed position on the stage 65, and control the
The direction drive motors 66 and 67 are operated to move the stage 6.
5 to the inspection start position of sample 74,
Further, the Z direction fine movement micrometer 68 and the θ direction moving ring 69 are operated 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, 9
After setting the ion beam extraction conditions of small current, low accelerating voltage, and wide scanning range on the sample 74 for observation and defect inspection of the sample 74,
observation and defect inspection.

Then, the liquid metal ion source 75 is powered by the power source 86.
A current is supplied to the filament of the
When a negative voltage of several KV to several tens of KV is applied to the extraction electrode 77 by the power supply 88 in a vacuum of 10 ^-5 torr or less, an extremely narrow area at the tip of the chip provided on the filament of the liquid metal ion source 75 is applied. An ion beam 78 is extracted from. When extracting the ion beam 78, the control electrode 76 is connected to the liquid metal ion source 7 through the power supply 87.
A low positive and negative voltage is applied near the tip of the filament No. 5 to control the current.

The ion beam 78 extracted from the liquid metal ion source 75 has only its central portion taken out by an aperture 79, and is further connected to power sources 89 and 90.
Electrostatic lenses 80, 81 to which a voltage is applied
and another electrostatic lens 82 to form a spot 78' of 0.5 μφ or less, and is deflected in the X and Y directions by deflection electrodes 84 and 85 activated by voltage applied from a power source 93. A spot 78' is formed on the surface, and the surface of the sample 74 is irradiated with an 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 received by the secondary charged particle detector 95, and their intensity is converted into an electric current and the SIM
It is sent to the observation device 96.

The SIM observation device 96 also includes a power source 9 for the deflection electrode.
3 receives a signal regarding the amount of deflection of the ion beam 78 in the X and Y directions, scans a bright spot on the cathode ray tube 97 in synchronization with the signal, and compares the brightness of the bright spot with the current intensity from the secondary charged particle detector 95. By changing the angle according to the angle, an image of the sample 74 is obtained at each point, and the sample surface is observed under magnification.

Next, the sample 74 obtained with the SIM observation device 96
The image is recorded in the memory scope 98 of the inspection device for the sample 74.

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 the control device 103 of the drive system of the stage 65
Based on the image position information from the magnetic disk 10
The information on the pattern at the position corresponding to the image of the sample 74 is extracted from the information on the original pattern stored in 0, the image of the sample 74 and the information on the original pattern are compared, and if the two do not match, it is determined to be a defect. It is determined that there is.

In this way, by using the secondary electron image or the secondary ion image obtained by scanning the ion beam 78 with a diameter of 0.5μ or less, it is possible to inspect defects in patterns of 0.5μ or less.

After observing and inspecting the sample 74, the blanking electrode 83 is activated, the ion beam 78 is scanned at an extremely high speed, and the ion beam 78 is removed outside the aperture 79', and the irradiation of the ion beam 78 onto the sample 74 is stopped at high speed.

When a defect is detected in the pattern of the sample 74 by the comparison circuit 99 of the inspection device for the sample 74,
The control system 102 is switched to the conditions for extracting the ion beam 78 of large current, high accelerating voltage, and narrow scanning area suitable for correction, the large current ion beam 78 is extracted from the liquid metal ion source 75, and the high accelerating voltage is applied by the control electrode 76. give, electrostatic lens 8
0,81,82 to focus the ion beam 78 on a spot of 0.5μφ or less and deflection electrodes 84,85.
The scanning range is limited, the ion beam 78 is irradiated to the defect position of the pattern, and the defect is corrected by sputtering removal. Alternatively, the ion beam 78 may be imaged and projected onto the defect position to remove the defect by sputtering.

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

After correcting the pattern defects of the sample 74,
It is also possible to switch the control system again to values suitable for observing and inspecting the sample 74, repeating the above-described operations, and inspecting 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 binary circuit is connected to the secondary charged particle detector 95, and the signal is converted into a binary signal of 0 level and 1 level depending on whether it is higher or lower than the reference level, and then sent to the SIM observation device. You may also do so.

〔Effect of the invention〕

As explained above, according to the present invention, a high-brightness ion source is provided, and when forming a SIM image of a repaired part on a workpiece using an observation means, an ion beam spot of 0.5 μm or less is limited to the repaired part. By providing a control means for controlling the deflection electrode to change the scan range of the ion beam spot of 0.5 μm or less when irradiating and processing the ion beam, the charged particle optical system outputs a high-intensity ion beam. It is possible to focus the irradiation onto a spot of 0.5 μm or less on the workpiece, and to obtain the energy that enables fine processing of 0.5 μm or less. As a result, SIM It is possible to observe the repaired part on the workpiece with high resolution using an image, and it also has the effect of realizing fine processing of 0.5 μm or less with high accuracy, which is limited to the repaired part.

[Brief explanation of drawings]

Figures 1a and b are cross-sectional views showing an example of a mask that is symmetrical in the present invention, Figure 2 is a plan view of the same, Figure 3 is a diagram showing a conventional example of a mask defect inspection device, and Figure 4a , 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. be. DESCRIPTION OF SYMBOLS 10, 11, 12... Defect in the wiring pattern of the mask, 47... Frame, 49... Vacuum container, 50... Sample chamber, 51... Sample exchange chamber, 54-64... Members constituting vacuum evacuation means, 65... Stage ,66,67...
X, Y direction drive motor, 68... Z direction fine movement micrometer, 69... θ direction moving ring, 70... Sample stage, 71 to 73... Rotation introduction terminal, 74... Sample which is a mask, 75... High brightness ion source Liquid metal 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
...SIM observation device, 98...Memory scope, 99...
Comparison circuit for comparing the sample pattern image and original pattern information, 100... Magnetic disk for storing original pattern information, 102... Control system for switching power supply operating conditions between observation/inspection and defect correction, 103
...Control device for the drive system of the stage.

Claims (1)

[Claims] 1 A high-intensity ion source, an extraction electrode for extracting a high-intensity ion beam from the high-intensity ion source, and a spot of 0.5 μm or less in size for the high-intensity ion beam extracted from the extraction electrode onto a workpiece having a fine circuit pattern. an electrostatic lens that focuses the focused ion beam, a deflection electrode that deflects the focused ion beam focused by the electrostatic lens, and a block that controls and stops the irradiation of the high-intensity ion beam to the workpiece having the fine circuit pattern. Secondary charged particle detection that detects secondary charged particles generated from the workpiece having the fine circuit pattern using the ranking electrode and the ion beam spot that is focused to 0.5 μm or less by the electrostatic lens and scanned by the deflection electrode. an observation means for forming and observing a SIM image of a repaired part on the workpiece based on the secondary charged particle signal obtained from the secondary charged particle detector; The deflection electrode is used to change the scan area of the ion beam spot of 0.5 μm or less when forming a SIM image of the repaired area and when processing by irradiating the ion beam spot of 0.5 μm or less to the repair area. An ion beam processing apparatus comprising: a control means for controlling the ion beam processing apparatus;