JP4804136B2 - Charged particle beam apparatus and device manufacturing method - Google Patents

Description

The present invention relates to a charged particle beam apparatus that scans a minute field on each of a plurality of charged particle beams .

When manufacturing microdevices (semiconductor chips such as IC and LSI, liquid crystal panels, CCDs, thin film magnetic heads, micromachines, etc.), a charged particle beam exposure apparatus is used to form a pattern on a sample. The charged particle beam exposure apparatus accelerates, shapes, and reduces charged particles emitted from a charged particle source, and forms a desired pattern on the sample by irradiating the sample with a beam. In many types of exposure apparatus, charged particles are shaped and reduced, and then irradiated onto a sample. However, particularly when the throughput of the exposure apparatus is required, a method has been devised in which a plurality of beams are generated and a plurality of patterns are simultaneously drawn by being controlled independently.
A typical example is shown in Patent Document 1 as a method for controlling the charged particle beam described above. In this conventional example, the electron beam emitted from one electron source is divided into a plurality of beams and irradiated onto the sample, and irradiation and non-irradiation of each beam are controlled by a multi-blanker and a blanking control circuit. Has been.
Japanese Patent Laid-Open No. 9-245708

By the way, in the above conventional example, the expected resolution and drawing accuracy may not be obtained. This is due to the following reason according to the knowledge of the present inventors.
That is, in the above-described conventional example, drawing is performed by scanning each minute field with a plurality of beams and controlling each beam on and off. Here, considering the process of drawing a certain pattern, each beam is turned on when it reaches the drawing pattern position by deflection scanning, and is turned off when it is not the drawing pattern position. When this operation is considered for all the beams, the total beam current reaching the wafer fluctuates in time series. That is, the beam current is maximized at the time when all the beams are related to drawing, and conversely, when all the beams are not drawn, the beam current is minimized (zero). Therefore, drawing proceeds while the beam current always varies between 0 and the maximum value.
On the other hand, the resolution of the beam focused on the sample is deteriorated by the influence of the Coulomb effect, and the beam current and the resolution by the Coulomb effect are in a substantially proportional relationship. Considering the above two points, the beam current fluctuates with the beam scanning during drawing and the turning on / off of each beam, resulting in fluctuations in resolution. When individual beams are turned on and off randomly, the beam current fluctuations do not become very large, but the specific situations described below involve very large current fluctuations.
For example, consider the case of drawing a line and space pattern. If the fine field size on which deflection scanning is performed is an even multiple of the pattern dimension, all the beams are turned on simultaneously in a certain pixel drawing, and are turned off simultaneously in the next pixel. The beam current in the on state is the maximum beam current, and the resolution is the worst. Similarly, considering the case of drawing a general device pattern, if a very small field size is set to an even multiple of the design rule, a phenomenon similar to the above occurs and a very large beam current fluctuation occurs. That is, almost all of the beams are simultaneously turned on at a certain time, and almost all of the beams are simultaneously turned off at a certain time. And the resolution of the pattern drawn when almost all the beams are turned on and the pattern drawn when almost all the beams are turned off at the same time are greatly different. This greatly affects not only the resolution but also the drawing accuracy.
An object of the present invention is to solve the problems in the above-described conventional example.

The present invention is a charged particle beam apparatus that generates a plurality of charged particle beams and scans a micro field on each of the plurality of charged particle beams,
Charged particles comprising setting means for setting a size of the minute field so as not to be an even multiple of a drawing pattern size of a line and space pattern to be drawn in the minute field in the scanning direction It is a wire device .

According to the present invention, it is possible to realize a charged particle beam apparatus that is advantageous in reducing the influence of the Coulomb effect.

Hereinafter, preferred embodiments of the present invention will be described with reference to examples.
In the following, an example of a multi-electron beam exposure apparatus is shown as an example of a charged particle beam. The following embodiments can be applied not only to an electron beam but also to an exposure apparatus using an ion beam, and the same effect can be obtained not only to the exposure apparatus but also to other multi-beam charged particle beam apparatuses. it can.

[First embodiment]
The first embodiment will be described below.
FIG. 1 is a schematic view of the main part of an electron beam exposure apparatus according to an embodiment of the present invention.
In FIG. 1, an electron beam emitted radially from an electron source 1 is shaped into an area beam having a desired size by a collimator lens 2, and is then substantially perpendicularly incident on a mask 3. The mask 3 is a mask having a plurality of openings. The electron beam 10 divided into a plurality of shapes through the mask 3 is converged on the blanking array 6 by the lens 4. The blanking array 6 is a deflection plate array and can deflect individual beams. The beam deflected by the blanking array 6 is blocked by the blanking stop 9. On the other hand, the undeflected beam is converged by the lens 7 and passes through the blanking stop 9. Further, the light is converged by the lens 8, the irradiation position on the sample is adjusted by the deflector 5, and then the sample 11 is irradiated.

  The deflector 5 performs a raster scan, and a beam is irradiated to a desired position according to the scan timing of the deflector 5 and the operation timing of the blanking array 6. Each lens 2, 4, 7, 8 is controlled by a lens control circuit 13, and the deflector 5 is controlled by transmitting a raster deflection signal generated by a deflection signal generation circuit 18 to a deflection amplifier 19. The blanking array 6 is controlled by a blanking control circuit 17. The blanking control circuit 17 is controlled by a blanking signal generated by the drawing pattern generation circuit 14, the bitmap conversion circuit 15, and the exposure time control circuit 16.

Next, the movement of the beam on the sample will be described with reference to FIGS.
FIG. 2 illustrates the movement of all the beams that reach the sample. Each beam 10 raster scans the minute field 20 assigned to each beam 10 and draws a pattern. Further, all the beams simultaneously perform the same raster scan, and individually turn on / off the beams according to the pattern to draw the pattern in the field 22.
FIG. 3 shows the beam motion and pixel structure within one microfield. As described above, one beam 10 performs a raster scan in the minute field 20, but the minute field is further divided into pixels 21, and a pattern is drawn by turning on and off the beam for each pixel.

  Next, FIG. 4 illustrates the movement of a plurality of beams in the conventional example only for two minute fields. FIG. 4A shows an example in which two micro fields described in FIG. 3 are arranged. Each beam 10 raster scans each microfield 20. At this time, considering the drawing of the line and space pattern shown in FIG. 4B, each beam is individually turned on / off by blanking, but the on / off timing is exactly the same. That is, the beam is turned on at the same time and the beam is turned off at the same time. FIG. 4C shows the beam current fluctuation on the sample at this time. The beam current becomes maximum when the beam is on and becomes zero when the beam is off.

  On the other hand, the beam current and the beam resolution are related by the Coulomb effect, and the beam resolution deteriorates as the beam current increases. That is, considering the example described with reference to FIG. 4 for all the beams, when a line and space pattern is drawn as shown in FIG. 4, the sample is irradiated with the maximum current, and the beam resolution is the highest. It will be drawn in a bad state. In the above description, only the line and space pattern is drawn. However, when another pattern exists in addition to the line and space pattern, the following is performed. That is, the line and space pattern has a low resolution, and other patterns are drawn with a high resolution. This greatly affects not only the resolution but also the drawing accuracy. The cause of the above problem is that the minute field size is set to an even multiple of the pattern dimension.

  Next, FIG. 5 shows a drawing method according to the present embodiment. In FIG. 5, in order to avoid the above problem, the minute field pattern size is set to an odd multiple of the drawing pattern dimension. Considering a minute field adjacent to one minute field, when one beam is in an on state, the other beam is in an off state, and the on / off state of the beam is always reversed. That is, a constant beam is always irradiated on the sample. This description is the same even when all the beams are expanded. By setting the minute field pattern size to an odd multiple of the pattern dimension, drawing is performed in a state where a constant beam is always irradiated on the sample. . Even when the resolution of the beam is considered, the total beam current is halved compared to the above method, so that the resolution is improved. Further, there is no variation in resolution for each pattern, and accurate drawing is possible.

  In this embodiment, control means for automatically setting a minute field size to an odd multiple of the drawing pattern dimension is introduced into the controller 12 in order to realize the above method. In this embodiment, there is provided means for evaluating the pattern size of the drawing pattern and setting the minute field size to an odd multiple thereof. In addition, when the drawing pattern is large, a means for extracting some representative patterns is provided.

  The exposure was actually performed using the method described above. In the first experiment, a line-and-space pattern having a pixel size of 50 nanometers and a fine field size of 2 microns with a pitch of 100 nanometers was drawn. In the second experiment, a line and space pattern having a pitch of 100 nanometers was drawn with a pixel size of 50 nanometers and a fine field size of 2.05 microns. As a result, it was possible to improve the drawing result, which was 70 nm in pattern resolution in the first experiment, to 50 nm in the second method.

In the present embodiment, the resolution can be improved by setting the minute field size to an odd multiple of the drawing pattern dimension. However, the effect is not limited to an odd multiple of the drawing pattern dimension, and the same effect as described above can be obtained if it is not an even multiple. Similarly, the same effect can be obtained by setting the minute field size not to be an even multiple of the pixel size. Further, a better effect can be obtained by calculating and setting the minute field size based on the drawing pattern so that the temporal fluctuation of the beam current on the sample calculated from the drawing pattern is minimized.
In the above description, the example of one electron source is shown, but two or more electron sources may be used.

[Second Embodiment]
Next, a second embodiment will be described.
Although the minute field size is changed by data control in the first embodiment, the same effect is realized by changing the optical parameter in this embodiment.
Consider changing the minute field size in the first embodiment and setting a minute field size one pixel larger than the conventional minute field size. Then, as shown in FIG. 2, since the minute fields 20 are arranged in 8 × 8, the outermost minute minute field needs to be shifted by 3 pixels, and the field size 22 is increased by 6 pixels. In consideration of further enlargement of the minute field size, the shift amount of the outermost minute field increases with the enlargement, and finally exceeds the scannable region of the outermost minute field. Therefore, the first embodiment is not sufficient when the change amount of the minute field size is large.

Therefore, in the second embodiment, the reduction ratio of the optical system is changed as the minute field size is changed. That is, the excitation of the lenses 7 and 8 is changed. Changing the reduction ratio of the optical system means changing the pitch of the minute field. Therefore, if the reduction ratio of the optical system is increased by x%, the minute field size can be enlarged by x% without shifting the minute field. By performing raster scanning and on / off control of each beam in the same manner as in the first embodiment, drawing similar to that in the first embodiment can be performed.
In this embodiment, the minute field size change amount is calculated in the same manner as in the first embodiment in order to change the reduction ratio, and then the lens change amount is calculated by the controller 12, and the lens data is sent to the lens control circuit 13. Forward. Further, for fine adjustment of the optical system, fine adjustment is performed using a beam calibration means.

  The exposure was actually performed using the method described above. In the first experiment, a line-and-space pattern having a pixel size of 50 nanometers and a fine field size of 2 microns with a pitch of 100 nanometers was drawn. In the second experiment, a line-and-space pattern with a pixel size of 50 nanometers and a fine field size of 2.15 microns with a pitch of 100 nanometers was drawn. When changing the minute field size, the excitation of the lenses 7 and 8 was changed as described above. As a result, similar to the first example, the drawing result, which was the pattern resolution of 70 nanometers in the first experiment, was improved to 50 nanometers in the second method.

[Third embodiment]
Next, a manufacturing process of a micro device (a semiconductor chip such as an IC or LSI, a liquid crystal panel, a CCD, a thin film magnetic head, a micromachine, etc.) using the above exposure apparatus will be described.
FIG. 6 shows a flow of manufacturing a semiconductor device.
In step 1 (circuit design), a semiconductor device circuit is designed. In step 2 (EB data conversion), exposure control data for the exposure apparatus is created based on the designed circuit pattern.
On the other hand, in step 3 (wafer manufacture), a wafer is manufactured using a material such as silicon. Step 4 (wafer process) is called a pre-process, and an actual circuit is formed on the wafer by lithography using the wafer and the exposure apparatus to which the prepared exposure control data is input.
The next step 5 (assembly) is called a post-process, and is a process for forming a semiconductor chip using the wafer manufactured in step 4. The post-process includes assembly processes such as an assembly process (dicing and bonding) and a packaging process (chip encapsulation). In step 6 (inspection), the semiconductor device manufactured in step 5 undergoes inspections such as an operation confirmation test and a durability test. A semiconductor device is completed through these processes, and is shipped in Step 7.

  The wafer process in step 4 includes an oxidation step for oxidizing the surface of the wafer, a CVD step for forming an insulating film on the wafer surface, and an electrode formation step for forming electrodes on the wafer by vapor deposition. Also, an ion implantation step for implanting ions into the wafer, a resist processing step for applying a photosensitive agent to the wafer, and an exposure step for printing and exposing the circuit pattern on the wafer after the resist processing step by the exposure apparatus described above. Further, there are a development step for developing the wafer exposed in the exposure step, an etching step for removing portions other than the resist image developed in the development step, and a resist stripping step for removing the resist that has become unnecessary after the etching. By repeating these steps, multiple circuit patterns are formed on the wafer.

It is a figure which shows the principal part outline of the electron beam exposure apparatus which concerns on one Example of this invention. It is a figure for demonstrating the motion of the micro field in a field and the beam which concerns on 1st Example of this invention. It is a figure for demonstrating the motion of the pixel in the micro field in FIG. 2, and a beam. It is a figure for demonstrating the motion of the beam in two micro fields in the prior art example, pattern drawing, and beam current fluctuation | variation. It is a figure for demonstrating the motion of the beam in 2 micro fields which concern on the said 1st Example, pattern drawing, and beam current fluctuation | variation. It is a figure explaining the flow of the manufacturing process of a device.

Explanation of symbols

1: Electron source 2: Collimator lens 3: Mask 4: Lens array 5: Deflector 6: Blanking array 7, 8: Lens 9: Blanking stop 10: Beam 11: Sample 12: Controller 13: Lens control circuit 14: Drawing pattern generation circuit 15: Bitmap conversion circuit 16: Exposure time control circuit 17: Blanking control circuit 18: Deflection signal generation circuit 19: Deflection amplifier 20: Minute field 21: Pixel 22: Drawing field

Claims (7)

Generating a plurality of charged particle beams, a respective charged particle beam apparatus Ru is scanned a small field in the plurality of charged particle beam,
In the direction of the scan, so as not to even multiple of the drawing pattern size of the line and space pattern to be drawn in said micro field, comprising a setting means for setting the size of the micro field, it shall be the said charge Particle beam device. The setting means, the charged particle beam apparatus according to claim 1, wherein setting the size of the micro field so the odd multiples of the drawing pattern dimensions, characterized in that. Having a calculating means for calculating the size of the set Teisu should the fine field based on the drawing pattern, it charged particle beam apparatus according to claim 1 or claim 2, characterized in. Before SL calculated hand stage is to extract a portion of the drawing pattern, to calculate the size of the micro-fields based on the extracted pattern, the charged particle beam apparatus according to claim 3, characterized in that. Before SL calculated hand stage, according to claim 3 or claim 4 time variation of the total current onto the sample to be more calculated drawing pattern to calculate the size of the micro field becomes minimum, characterized in that Charged particle beam device. An optical system for irradiating on the sample by reducing the plurality of charged particle beams, the size or et reduction ratio of the optical system of the calculated micro fields by said calculating means calculates the reduction ratio which is the calculated and so as to the change of the reduction ratio of the optical system, charged particle beam device according to any one of claims 1 to 5, wherein. Device characterized in that it comprises a step of exposing a substrate using a charged particle beam equipment according to any one of claims 1 to 6 and a step of developing the substrate exposed in the step Production method.

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