JPS60126826A - Electron beam exposing device - Google Patents

Abstract

PURPOSE:To reduce the transition time of an electron beam by a method wherein the first electron beam deflecting device with which the desired region of a sample will be determined, the second electron beam deflecting device with which region 1 will be determined, and the third electron beam deflecting device to be used to perform an exposure on a single unit pattern are provided. CONSTITUTION:The light of a microscopic electron light source 1 is made to irradiate on the first aperture 4 through the intermediary of an irradiation lens 3, and its image is image-formed on the second aperture 7 using a forming lens 6. The cross section of an electron beam is formed into the rectangular beam of arbitrary size using a beam forming deflector 5. Said rectangular beam is reduced by reduction lens 8 and projected on the surface of a sample 11 by a projection lens 9. The irradiation position on the surface of the sample 11 is set by the movement of a stage 12 and the first deflector 20a, the second deflector 20b and the third deflector 20c, an ON or OFF position is given to the electron beam by the blanking electrode which is operated in synchronization with a positioning deflector, and an exposure is performed.

Description

Detailed Description of the Invention (a) Technical Field of the Invention The present invention relates to an electron beam exposure apparatus, particularly an electron beam exposure apparatus that achieves pattern accuracy and exposure processing time suitable for direct exposure of wafers of ultra-large scale semiconductor integrated circuit devices. Regarding.

(b) Background of the technology As the scale of semiconductor integrated circuit devices (hereinafter abbreviated as IC) increases, the miniaturization and density of their patterns are being promoted, and what is the microfabrication technology to realize these patterns? ,
This is a combined technique of patterning a resist and etching a semiconductor substrate using the resist pattern as a mask.

As an exposure method for patterning a resist, the electron beam exposure method (a) has higher resolution than light and can draw minute figures with a minimum line width of about 0.1 [μm]. (b) Pattern position′! f1 degree is high,
High field of view or stripe joint accuracy).

Due to the above-mentioned feature (b), it is possible to draw a large pattern by continuing the field of view. 2) Input data can be processed by computer processing. (e) The number of steps is smaller compared to light exposure. Not only does it have high resolution, but it also functions as a pattern generator and shortens production time.

In manufacturing semiconductor devices, the electron beam exposure method can be applied to any of (1) reticle mask writing, (II) master mask writing, and (lil>wafer direct writing) due to the above-mentioned advantages.

(C) Prior art and problems The current electron beam exposure method aims to achieve both ultra-fine patterning and shortening of drawing time.

A variable rectangular beam system is often used using a device as illustrated in FIG. 1(ta).

In this method, the first aperture 4 is irradiated by the microelectronic light source II through the irradiation lens 3, and its image is formed on the second aperture 7 by the shaping lens 6i. By displacing the image using the beam shaping deflector 5, the cross section of the electron beam passing through the second aperture 7 can be shaped into a rectangular beam of any size.

This rectangular beam is reduced to the required size ζ by the reduction lens 8.
The irradiation position on the sample 11 is set by the movement of the stage 12 and the positioning main and sub-deflectors 10a and 10b. Exposure is performed by turning the electron beam on and off by the blanking electrode 2 which operates in synchronization with the electrode 10b. Note that FIG. 1(b) shows an example of the rice cake cylinder shape of the electron beam at each position.

Drawing by the above method is performed on the sample surface in Figures 2(a) to (
The process is divided into areas as exemplified in C).

Divide the mask blank or wafer 73 into fields with side lengths of 10 [7 nm], for example (Fig. 2(a)), and record this field as a field with side lengths of, for example, 100 [μm]. ) into subfields (second
(bl), drawing is executed in units of this subfield (FIG. 2(C)).

Selection of said field (by one stage movement).

The selection of the sub-field is performed by the main deflector 10a of the positioning deflectors, and the irradiation position within the sub-field is set by the sub-deflector 10b.

When drawing is executed, pattern data is processed as shown in the block diagram of FIG.
The data decomposer 22 decomposes the pattern into combinations of the variable rectangles based on the data regarding the pattern stored in the data decomposer 22 . A distortion correction circuit 2 uses this decomposed data of each irradiation.
In step 3, coordinate transformation is performed to eliminate pattern distortion caused by distance from the optical axis, etc., and the intensity of each irradiation is determined. These data are then converted into voltages or currents by digital/analog converters 24a, b and C and amplifiers 25a, b and C, respectively, to beam forming deflectors 5. The main deflector 10a and the sub deflector 10bl are input.

In the above-mentioned electron beam exposure method ζ, the main factors that determine the time required for exposure processing are the electron beam irradiation time and the transition time required to move to the next irradiation position after irradiation. The irradiation time is determined by the electron beam intensity and resist sensitivity.

The loss due to the transition time is dominated by the sub-deflection ζ.

Sub-deflection using an electrostatic deflector reduces the transition time by bringing the analog signal frequency forward. However, if the signal frequency band is expanded, the signal-to-noise ratio in the amplifier 25' decreases, resulting in an increase in the dimensional error of the drawn pattern. In conventional electron beam exposure, the allowable dimensional error of the pattern is, for example, 0.05 (
μm], the upper limit of the signal frequency is 10 (M)]i
Z), the minimum transition time is about 200 (ns).

In order to expose a wafer to a pattern of a very large-scale semiconductor integrated circuit device (hereinafter abbreviated as VLSI) with an electron beam, the time required for one irradiation, that is, the sum of the electron beam irradiation time and the average transition time, is is 100 (ns
It is desired to shorten the average transition time to about 20 (ns:1), for example, to about 20 (ns:1).

It is extremely difficult to achieve such time reduction without increasing dimensional errors using the above-mentioned exposure apparatus, and a novel electron beam exposure apparatus is being sought.

(di Purpose of the invention The present invention ensures good pattern accuracy.

It is an object of the present invention to provide an electron beam exposure apparatus in which the time required for exposure processing, particularly the electron beam transition time, is shortened.

(e) Structure of the Invention The object of the present invention is to provide a first electron beam deflection means for determining a desired region of a sample, and a second electron beam deflection means for determining one region within the desired region.

This is achieved by an electron beam exposure apparatus that is equipped with a third electron beam deflection means for exposing the unit pattern within the l area, and is configured to sequentially and repeatedly expose the unit pattern within the desired area.

That is, the electron beam exposure apparatus according to the present invention includes the following means for achieving the above object.

(1) Reduction of the minimum area division of the drawing surface and expansion of the deflector frequency band within the division area.

As explained above, the factor that restricts the shortening of the electron beam transit time using an electrostatic deflector is the deterioration of the signal-to-noise ratio due to the expansion of the signal frequency band. In the present invention, the amplitude of the deflection signal frequency is reduced by reducing the minimum area division (the subfield), and the amplitude is reduced to the extent of the square of the reduction ratio, without increasing the absolute value of the noise component. This makes it possible to expand the signal frequency band.

(11) Three stages of electron beam positioning deflection.

In order to carry out the selection of the reduced minimum segmentation area without loss of accuracy and with comparable transition times, the first deflector, typically of the electromagnetic type, is selected as before. and a second deflector, typically of electrostatic type, driven by a frequency band signal.

Furthermore, the effects of the present invention are expanded by the following means.

(+::) 4° In the conventional electron beam exposure method, the division of the subfields is 1 Normally set on the exposure device side regardless of the pattern to be drawn. As a result, even in memory devices and the like in which the same elements are arranged periodically, the subfields generally do not match the pattern and the feature that the same elements are arranged periodically is not utilized.

In contrast, in the exposure apparatus of the present invention, the minimum area division is set in accordance with the period of the pattern.7 As a result, the minimum area division is not necessarily uniform in size and on a constant module throughout the entire drawing surface. Even if it is not set, the second
The selection can be easily made using the deflector of
Kokichi can effectively utilize the periodicity of the pattern.

(f) Embodiments of the Invention The present invention will be specifically described below by way of embodiments with reference to the drawings.

An embodiment of an electron beam exposure apparatus according to the present invention is shown in FIG. This exposure apparatus is provided with a first deflector 20a, a second deflector 20b, and a third deflector 20c as positioning deflectors. The first deflector 20a is of an electromagnetic type and has a severe double amplitude IQ (in).

The second deflector 2Qb is an electrostatic type with a maximum amplitude of 400 μm.
), the third deflector 20c is an electrostatic type with a maximum amplitude of 25
[μm] is obtained with an error of about 0.05 (μm) or less.The analog signal bandwidth of the third deflector 20C is expanded to 100 CMHz or more, and the transition time is is 20 (ns) or less. An example of VLSI pattern drawing using the electron beam exposure apparatus will be explained. FIG. Also, Fig. 5 (bl is 32, 33, 36 of the above pattern) is shown.
The details of the patterns that often appear in the and 37 sections are shown.

In this exposure process, the drawing surface, for example, the wafer surface, is divided into three regions as shown in FIGS. 6(a) to 6(C).

That is, as shown in FIG. 6(a), the entire drawing surface is divided into primary divided regions with each side being less than or equal to the maximum amplitude of the first deflector 20a and having a shape and size that is usually the chip size or an integral multiple thereof. Set 41. This selection of the primary divided area 41 is performed by moving the stage.

In the primary divided area 41, as shown in FIG. 6(b)l, a secondary divided area 42 whose side is less than or equal to the maximum amplitude of the second deflector 20b is added to the secondary divided area 42f as shown in FIG. As shown in C), one side of the third division area 43 is set below the maximum double amplitude plate of the third deflector 20c.

The selection of the secondary segmented area 42 is performed by a first deflector 2. Usually, the center point of the secondary segmented area 42 is used as a reference point, and the electron beam is directed to the first deflector to select this reference point. give a deflection towards. Further, the selection of the tertiary segmented area 43 is similarly performed by the second deflector.

In this embodiment 1, in the pattern to be drawn, as shown in FIG.
), many periodic repeating patterns appear, and in this part, as shown in Figure 6 ((1),
The shape and dimensions of the tertiary divided area 43 are set to be an integral multiple of the pattern period, and this is used as a unit pattern, and its position is matched so that the number of electron beams irradiated is at most /J%.

When the tertiary divided areas 43 are set in this manner, their shapes and dimensions are not necessarily uniform, and their positions are not necessarily arranged on modules at regular intervals within the upper divided area. (See FIG. 6(C)) However, this non-uniformity can be countered by deflecting the electron beam to the reference point of the unit pattern area of the tertiary division by the second deflector 20b at unequal intervals. I can do it.

That is, in the electron beam exposure apparatus of the present invention, the data of each electron beam irradiation is transmitted to the first deflector (Xn, Yn
), second deflector (ξn, ηn) + third deflector (
xn, yn) and beam shaping deflectors (an.

data for the third deflector and the beam shaping deflector for the range in which the same pattern is repeated as described above and the unit pattern area is set in accordance with the cycle of b1]). (xn, yn) and (an
, bn) are the same. Note that the data (ξn, ηn) for the second deflector is not necessarily a static difference sequence.
As mentioned above, in the present invention, the electron beam positioning deflection is performed in three stages to reduce the minimum area division compared to the conventional one, and as a result, the electron beam transition time is reduced to about 1/10 of the conventional one without reducing pattern accuracy. However, as explained above, the speed can be further increased by actively utilizing the repetition period of the pattern.

In other words, the data portions (xn, yn) and (an, bn) that are repeated many times are stored in a RAM that uses normal data storage.
Great effects can be achieved by accommodating the electron beam in a shift register capable of higher-speed reading, or by using an electron beam with a shape other than rectangular rather than limited to a general variable rectangular beam to reduce the number of irradiations.

(g) As described in detail, according to the present invention, the electron beam transition time is significantly reduced compared to the conventional method without deteriorating pattern accuracy, making it possible to shorten the required time for electron beam exposure processing. This has a great effect on the promotion of electron beam exposure for VLSI devices, etc.

[Brief explanation of the drawing]

Figures 1 (a) and (bl) are explanatory diagrams of a conventional variable rectangular electron beam exposure system, Figures 2 (a) to (C1 are explanatory diagrams of conventional drawing area divisions, and Figure 3 is an explanatory diagram of conventional data transfer. FIG. 4 is a diagram showing an embodiment of the electron beam exposure apparatus of the present invention, FIG. 5(a) and fb) are plan views showing patterns of the embodiment of the present invention, and FIG. 6(a) 7(d) are explanatory diagrams of drawing area divisions in the embodiment of the present invention. In the figures, 1 is a microelectronic light source, 2 is a blanking electrode, 3 is an irradiation lens, 4 is a first aperture, and 5 is a beam shaping device. Deflector, G is molded lens, 7 is second aperture B
8 is a reduction lens, 9 is a projection lens, 11 is a sample, 12 is a stage, 20a to C are first to third positioning deflectors, 31 to 38 are parts of the VSLI pattern, 41 is a first division area, Reference numeral 42 indicates a second divided area, and numeral 43 indicates a third divided area. 2nd group (0L) (b) (C) Figure 3 Figure 5 Tadashi Cb)

Claims (1)

[Claims] A first electron beam deflection means for determining a desired region of the sample, a second electron beam deflection means for determining one region within the desired region, and a third electron beam deflection means for exposing a unit pattern within the one region. 1. An electron beam exposure apparatus, comprising an electron beam deflecting means, and configured to sequentially and repeatedly expose the unit pattern within the desired area.