JPH0789530B2 - Charged beam exposure device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a charged beam exposure apparatus using an electron beam or an ion beam used for forming a fine pattern required for manufacturing semiconductor integrated circuits and the like.

[Prior Art] Conventionally, as an exposure apparatus using a charged beam, an exposure apparatus according to each of (1) spot beam method, (2) shaped beam method, (3) multi-beam method, and (4) mask transfer method has been used. Being developed. The spot beam method of (1) has a drawback that the exposure time is long because a single finely focused beam scans the sample surface to perform pattern writing. The shaped beam method of (2) is a method of forming a fixed or variable rectangular beam and drawing a pattern for each rectangle. However, even with this method, since exposure is performed with one beam,
As the pattern becomes finer, the throughput cannot be said to be sufficient. (3) The multi-beam method is a method in which a large number of beams are simultaneously generated to draw a pattern, and the drawing time is shorter and higher than the case of using one beam as in the above (1) and (2). Throughput can be expected. (4)
The mask transfer method is a method in which an image of a mask on which a pattern is formed in advance is imaged on the sample surface in a one-to-one or reduced form and is exposed. As the mask, there are a mask having a beam transmission hole formed in a thin metal plate and a mask using a photo emitter. In this method, since it is necessary to prepare a mask pattern in advance, an arbitrary pattern cannot be generated electrically. Further, there is a difficulty in manufacturing a mask, and more accurate alignment becomes a problem. That is, it is difficult to align the mask and the wafer, and the distortion of the electron optical system and the distortion of the chip cannot be corrected, which is a practical problem.

The multi-beam method of (3) above is an advantageous method compared to the methods of (1) and (2). In the conventional multi-beam method, a large number of aperture lenses are two-dimensionally arranged as shown in FIG. There is known an exposure apparatus that uses a matrix lens arranged in a linear manner. In FIG. 8, the beam emitted from the electron gun 801 and passing through the irradiation lens 802 and the blanker 803 is
The forming diaphragm 804 is illuminated and the image of the forming diaphragm 804 is a two-stage deflector.
After passing through 805, images are formed on the sample surface 808 by the respective lenses 807 constituting the matrix lens, and a multi-beam is obtained. Each aperture lens 807 of the matrix lens is illuminated with a beam of uniform intensity through the limiting diaphragm 806. The two-stage deflector 805 has a function of scanning the multi-beam on the sample surface 808 similarly. Pattern drawing is performed by combining the functions of the two-stage deflector 805 and the blanker 803. In the above exposure apparatus, since one beam corresponds to one chip of the integrated circuit, the aperture lens 80 forming the matrix lens
The array of 7 matches the pitch of the chip.
For example, if the chip pitch is 10 mm, the aperture lens array will be 10 mm apart, and if the array is 10 × 10, it will be 90 mm.
It will occupy the corner. If such a matrix lens is used, a large number of chips can be exposed at one time, so high-speed drawing becomes possible.

[Problems to be solved by the invention]

As described above, the multi-beam method is capable of high-speed drawing, but since the limiting diaphragm 806 usually has a diameter of at most several hundreds μm, only a very small number of the beams passing through the forming diaphragm 804 are incident on the matrix lens. Illuminates the sample surface,
Most of the beam current obtained from the electron gun 801 is wasted. Yet another problem is that the matrix lens has to be irradiated with a beam of uniform intensity over a wide range, for example, 90 mm square. Therefore, a large value is required for the emittance of the electron gun 801. However, high brightness is required to secure a large beam current.
It is difficult to increase the emittance of 801. As described above, the conventional multi-beam exposure apparatus has a large amount of beam current. Also, due to the emittance constraint of the electron gun, when the matrix lens array is enlarged, the brightness of the electron gun is reduced, the beam current is further reduced, and it is difficult to greatly improve the throughput. Further, in a device using a matrix lens, variations in deflection distortion of each beam cannot be avoided. Therefore, when performing overlay exposure, it is necessary to independently deflect each beam and correct the position to correct the distortion. Therefore, there is a problem that the structure of the exposure apparatus becomes complicated.

[Means for Solving the Problems] The present invention solves the above problems, increases the beam current of a multi-beam type exposure apparatus to improve throughput, and realizes highly accurate alignment with a simple configuration. It is an object of the present invention to provide a charged beam exposure apparatus that can be used. To achieve this object, a charged beam exposure apparatus according to the present invention includes a plurality of charged beam sources, a matrix blanker including a plurality of blankers, and a matrix deflector including a plurality of deflectors. In a charged beam exposure apparatus that forms a fine pattern on a sample by using multiple charged beams obtained from the charged beam sources of the above, a matrix lens is arranged between the charged beam sources and a matrix blanker, and the matrix deflector is provided after the matrix lens. The first lens composed of one lens common to a plurality of charged beams is arranged. The plurality of blankers forming the matrix blanker and the plurality of deflectors forming the matrix deflector can be independently controlled, and each deflector has a main trajectory of the charged beam passing through the center of the first lens. It was possible to control it so that it could pass through the neighborhood.

[Operation] In the charged beam exposure apparatus of the present invention, a plurality of charged beam sources are arranged in a matrix to increase the beam current, and a plurality of charged beam sources generated from the plurality of charged beam sources are used by using a matrix deflector. The charged beam passes near the optical axis of the lens to reduce lens aberration. High-precision drawing is performed by controlling the deflection of each electric beam independently by the matrix deflector.

〔Example〕

Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of a charged beam exposure apparatus according to the present invention, FIG. 2 is a view showing a forming diaphragm of the above embodiment, and FIG. 3 is a perspective view showing a matrix lens of the above embodiment. Four
FIG. 5 is a perspective view showing a matrix deflector, FIG. 5 is an explanatory diagram of aberrations in the above embodiment, (a) does not use a matrix deflector, (b) shows this embodiment, and FIG. 6 shows FIG. 7 is a configuration diagram showing another embodiment of the present invention, FIG. 7 is an explanatory diagram of an exposure operation by a variable shaping beam, FIG. 7A is a diagram showing rectangular openings of a first shaping aperture and a second shaping aperture, and FIG. [Fig. 4] is a diagram showing a beam that irradiates the sample surface through the rectangular opening. The 3 × 3 electron beams emitted from the matrix electron gun 101 in FIG.
Irradiation is performed so as to form a crossover on each of the three rectangular openings. The matrix electron gun 101 has three electron guns.
As shown in FIG. 2, square openings 201 having a side length L are arranged in a 3 × 3 pattern at a pitch of 4L, as shown in FIG. The matrix lens 103 is constructed as shown in FIG. The matrix lens shown in FIG. 3 is composed of an Einshell lens.
1 is a 3 × 3 array of lens apertures, 302 is a lens electrode, 30
3 is a lens power supply. An example of the matrix deflector 105 is shown in FIG. Here, 401 is an X deflection plate, and 402 is a Y deflection plate. The matrix deflector 105 is a parallel plate type deflector 3 ×
It is arranged in three. By applying an appropriate voltage to each X and Y deflection plate, the beam incident on each deflector can be deflected to a desired position. Further, as the matrix blanker 104, one having a configuration of 3 × 3 arrangement is used as in the matrix deflector shown in FIG. When an appropriate voltage is applied to the deflection plate of each blanker, the beam is deflected and the beam is cut by the blanking diaphragm 106 shown in FIG. The matrix blanker 104 can independently turn on / off 3 × 3 beams.

Next, the operation of the electron optical system in FIG. 1 will be described. First, the electron beam emitted from the electron gun 101 is irradiated onto a forming diaphragm 102 having rectangular openings arranged in a 3 × 3 array. The electron beam that has passed through the shaping diaphragm 102 enters the matrix lens 103. Further, the matrix lens 103 forms an image of each crossover at the deflection center of the matrix deflector 105. Next, the main trajectory of the electron beam is the objective lens 10
The matrix deflector 105 is operated so as to pass through the lens center of 7. Here, the center of the lens is a position where the beam incident on this position is emitted in the same direction as the incident direction. As shown in FIG. 5A, if there is no matrix deflector, some of the beams that have passed through the shaping diaphragm 501 include those that have passed away from the optical axis of the objective lens 502. On the other hand, in the present invention, each beam is arranged so that each beam passes through the center of the lens of the objective lens 502.
Since the light is deflected by, the beam that largely deviates from the optical axis 503 in the objective lens 502 can be eliminated. In general, as the beam deviates from the optical axis, the aberration of the lens increases. Therefore, in FIG. 5, (b) has a smaller aberration than (a).
Thus, the beam incident on the objective lens 107 is 3
The sample surface 109 is irradiated with three rectangular beams.

Next, the drawing operation will be described. The pixels of the exposure pattern correspond to one square beam whose one side is s (= L × magnification of optical system). The 3 × 3 square beams obtained on the sample surface are arranged in a 3 × 3 array with a pitch of 4S. Therefore, first, the deflector 108 scans the entire rectangular beam at an S pitch.
The exposure area having a size of 12S × 12S is scanned with a beam by deflecting each pixel in the Y direction and the Y direction. While performing such scanning, only when each square beam comes to the position to be exposed, the voltage previously applied to the matrix blanker 104 is set to zero and the beam is turned on, and the beam is turned to the desired position on the sample surface 109. The beam is emitted. 12S with the above exposure operation
The exposure in the range of × 12S is completed. Next, after the above exposure operation is completed, further 3 in the X and Y directions at a pitch of 12S.
The entire exposure beam of × 3 is deflected by the deflector 108 to perform the exposure operation. When the exposure area exceeds the maximum deflection area of the deflector 108, the sample is moved in the X and Y directions by the stage 110 with the size of the maximum deflection area as a unit, and the same exposure procedure is repeated. In this way, the entire area of the sample surface 109 is exposed. Here, the deflector 108 is one stage, but it is also possible to use two stages of deflectors to perform the S-pitch deflection and the 12S-pitch deflection by each deflector. Further, it is possible to adopt a method of exposing while the stage 110 is continuously moved. Positioning of drawing pattern is 3 × 3
The matrix blanker 104 is operated so that only one of the two beams reaches the sample surface 109, and this one beam is deflected by the deflector 108 to detect backscattered electrons from the mark formed on the sample. The mark position may be measured. The distortion caused by the beam deflection can be corrected by superimposing a deflection distortion correction signal on the deflector 108.

Next, FIG. 6 shows the configuration of another embodiment of the present invention. The matrix electron gun 601 has a 3 × 3 electron gun as in the previous embodiment.
The book is arranged. The matrix lens 603 is also the third
Lenses are arranged in a 3 × 3 array with a configuration similar to that shown in the figure. In the first and second shaping diaphragms 602 and 607, 3 × 3 square openings are arranged in the same manner as that shown in FIG. The matrix shaping deflector 605 and the matrix sub-deflector 608 are also 3 × 3 deflectors, and have the same configuration as that shown in FIG. Further, the matrix blanker 604 has the same configuration as that of FIG.
It consists of a blanka. The operation of the electron optical system in FIG. 6 will be described. The 3 × 3 electron beams emitted from the matrix electron gun 601 are respectively formed by the first forming diaphragm 60.
The distance between the electron gun 601 and the first shaping diaphragm 602 is set so that a crossover is created in the 2 × 3 × 3 opening.
The electron beams that have passed through the first shaping diaphragm 602 form a crossover at the deflection center of the matrix shaping deflector 605 by the matrix lens 603. A constant deflection voltage is applied to the matrix shaping deflector 605 in advance so that the main trajectory of the beam passes through the center of the reduction lens 606. The image of the first forming diaphragm 602 is changed to the second image by the reduction lens 606.
The image is reduced and formed on the forming diaphragm 607. A deflection voltage is applied to the matrix shaping deflector 605 according to a rectangular dimension to be exposed in order to obtain a variable shaped beam described later. Matrix blanker for each beam on / off
This is done by using 604. Here, the second shaping diaphragm 607 is used as a blanking diaphragm. Second
The image of the forming diaphragm 607 is formed on the sample surface 611 by the objective lens 609. The 3 × 3 beams on the sample surface 611 are independently deflected by the matrix sub-deflector 608. Further, the deflector 610 can collectively deflect the entire beam.

The pattern is drawn as follows. 3 × 3 in FIG.
2 shows a method of generating a variable shaped beam of. In FIG. 7A, 701 is a rectangular opening of the second shaping diaphragm, and 702 is an image of the first shaping diaphragm which is irradiated on the second shaping diaphragm. Since the image 702 of the first shaping diaphragm is deflected by changing the deflection voltage of the matrix shaping deflector 605, the beam in the portion where the image 702 of the first shaping diaphragm and the rectangular aperture 701 of the second shaping diaphragm overlap each other is the second beam. It passes through the forming diaphragm. The size of the beam that has passed through depends on the deflection voltage of the matrix shaping deflector. Next, FIG. 7B shows a state in which the beam passing through the second shaping diaphragm 607 is applied to the sample surface without operating the matrix sub-deflector 608. Here, 703 is a variable rectangular beam, 704 is the matrix sub-deflector 608, and the rectangular beam is deflected to a desired position within the deflection area 704 of the matrix sub-deflector 608. The voltage applied in advance to 604 is set to zero, the beam is turned on, and the beam is applied to the sample surface 611 to perform exposure. This operation is performed simultaneously in each of the 3 × 3 sub-trend regions 704. After this exposure operation is completed, the main deflector 610 is operated to move the entire 3 × 3 sub deflection area to the next exposure area, and the same exposure operation is performed. By repeating this, the entire pattern is exposed. When the exposure is performed beyond the maximum exposure area of the deflector 610, the stage 612 may be moved and then the exposure operation may be performed again in the same procedure. To align the drawing pattern, the matrix blanker 604 irradiates the sample surface 611 with one of the 3 × 3 beams, and the sample obtained when the one beam is deflected by the deflector 608. The mark position may be measured by detecting backscattered electrons from the mark formed in the above, and the mark position may be used as a reference. The distortion caused by the main deflection is the main deflector 610
It is corrected by superimposing a signal for correcting the deflection distortion on, and thereby highly accurate alignment can be performed. The deflection amount of the matrix deflector 605 is set in a range in which the deflection distortion is small and can be ignored.

In each of the above embodiments, an electron beam source using an electron gun may be used.

〔The invention's effect〕

As described above, the charged beam exposure apparatus according to the present invention is a charged beam exposure apparatus that forms a fine pattern using a charged beam, and includes a plurality of charged beam sources, a matrix lens, and a plurality of blankers that can be independently controlled. From the matrix blanker and a matrix deflector consisting of a plurality of deflectors that can be controlled independently, compared to a conventional device using a single beam,
Since a plurality of charged beam sources are used, the throughput capable of increasing the total beam current value is improved. Further, in the present invention, since the beams emitted from the plurality of charged beam sources are respectively deflected by the matrix deflector so that the beams pass in the vicinity of the optical axis of the lens, the lens aberration can be reduced. Therefore, the blur of the beam on the sample surface can be reduced, fine pattern writing can be performed, and the beam current can be increased, so that high throughput can be achieved. Further, since plural beams can be independently deflected, it is possible to draw efficiently, plural beams are projected by one lens, and when deflecting a large area, these are collectively deflected by one deflector, and the deflection distortion is corrected. Therefore, there is an effect that the device configuration is simplified.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of a charged beam exposure apparatus according to the present invention, and FIG. 2 is a view showing a forming diaphragm of the above embodiment,
FIG. 3 is a perspective view showing the matrix lens of the above embodiment, FIG. 4 is a perspective view showing the matrix deflector, and FIG. 5 is an explanatory diagram of aberrations in the above embodiment, and (a) is a matrix deflector. Not shown, (b) according to the present embodiment, FIG. 6 is a configuration diagram showing another embodiment of the present invention, and FIG.
The figure is an explanatory view of the exposure operation by the variable shaped beam.
Is a view showing a rectangular opening of the first forming diaphragm and the second forming diaphragm,
FIG. 8B is a diagram showing a beam pattern irradiated onto the sample surface through the rectangular opening, and FIG. 8 is a configuration diagram showing a conventional multi-beam type charged beam exposure apparatus. 101, 601 ... Charged beam source (electron gun), 103, 603 ... Matrix lens, 105, 504 ... Matrix deflector, 107, 502, 609 ... Lens (objective lens), 605 ... First matrix deflection 608, second matrix deflector (sub-deflector).

Claims (2)

[Claims] 1. A plurality of charged beam sources, a matrix blanker including a plurality of blankers, and a matrix deflector including a plurality of deflectors, wherein a plurality of charged beams obtained from the plurality of charged beam sources are provided. In a charged beam exposure apparatus for forming a fine pattern on a sample using, a matrix lens arranged between the plurality of charged beam sources and the matrix blanker, arranged between the matrix deflector and the sample,
A plurality of charged particles, the first lens being a single lens common to the plurality of charged beams, and the plurality of blankers forming the matrix blanker are independently controllable; A plurality of deflectors can be controlled independently so that a main trajectory of a charged beam passing through the deflectors passes near the center of the first lens. 2. A second matrix deflector comprising a plurality of deflectors arranged between the first lens and the sample, and arranged between the second matrix deflector and the sample, The charged beam exposure apparatus according to claim 1, further comprising a second lens that is a single lens common to the plurality of charged beams.