JPS6232613B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electron beam exposure method, and more particularly to a method for specifying an electron beam deflection position when drawing a diagonal pattern in a variable shape electron beam exposure method.

A variable shape electron beam exposure apparatus has already been proposed in order to shorten the drawing time by electron beam exposure.

FIG. 1a is a schematic diagram showing an example of a variable shape electron beam exposure apparatus, and FIGS. 1b and 1c show cross-sectional shapes of the electron beam at corresponding parts. In the same figure a, 1, 2, and 3 are cathodes, grids, and anodes that constitute the electron gun, 4 is a blanking deflector for blanking the electron beam during unnecessary periods, and 5 is a polygonal hole. 6 is an electronic lens; 7 is an imaging position of the image of the first diaphragm 5 which is formed by the first deflection device, that is, the electronic lens 6, onto a second diaphragm 8 having a polygonal hole. Control deflection device (deflector) 9 is a reduction lens, 1
0 is a converging lens, 11 is a second deflection device, that is, a positioning deflector (deflector), and 12 is a sample coated with resist, such as a semiconductor wafer.

The electron beam transmitted through the polygonal hole of the first aperture 5 and shaped into a polygonal pattern 13 is imaged by the electron lens 6 onto the second aperture 8 as a polygonal image 14 of the first aperture. The imaging position of the polygonal image 14 is controlled by the deflector 7, and the polygonal hole 1 of the second aperture 8
A cross-sectional shape 16 of a predetermined size is partially transmitted through 5,
An electron beam having an angle of 16' is obtained. The size and position of this electron beam are further controlled by a reduction lens 9, a convergence lens 10, and a positioning deflector 11, so that a desired pattern 17,
It is irradiated as an electron beam of 17'.

In order to draw a figure including the rectangular patterns 18, 18' and the diagonal pattern 19 as shown in FIG. Diagonal pattern 1 with pattern 17' electron beam
Expose 9 parts.

Of the four sides of the rectangular pattern 18, the sides AB and DA are formed by the overlap between the polygonal image 14 formed on the second aperture 8 and the polygonal hole 15 of the second aperture 8 shown in FIG. Among the four sides of the rectangle, polygonal hole 15
The two sides KL and NK of are projected, and point A corresponds to point K. Point K is one corner of the polygonal hole 15 of the second aperture, and is always used when drawing a rectangular pattern. Moreover, the projected position of point K can be determined only by the positioning deflector 11. Therefore, in order to designate the drawing position of a rectangular pattern, the amount of deflection of the electron beam by the positioning deflector 11 is controlled so that the projected position of point K becomes point A. That is, point K is used as a reference point when drawing a rectangular pattern. This is called the first reference point.

On the other hand, in the diagonal pattern 19, point E is c
Corresponds to one corner K' of the polygonal hole 15 of the second diaphragm shown in , and the point K' is always included in the diagonal pattern,
Moreover, the projection position is determined only by deflecting the electron beam with the positioning deflector 11. Therefore, point K' is used as a reference point for specifying the drawing position of the diagonal pattern. This is called the second reference point.

However, since points K and K' are in different positions,
When attempting to draw a figure that includes both a rectangular pattern and a diagonal pattern, it becomes extremely difficult to specify the irradiation position of the electron beam. That is, as shown in FIG. 2a, when the deflection amount OA is specified from the origin 0 of the electron beam deflection axes X and Y axes, the projected position of the first reference point K is set to point A. All rectangular pattern positions can be specified, but even if the deflection amount OE is specified to draw a diagonal pattern, point E becomes the projection position of the first reference point K, and the projection position of the second reference point is specified. Can not do it.

Therefore, in order to draw a diagonal pattern, some kind of operation is required to correct the amount of deflection, but no suitable method that can be put to practical use has hitherto been found.

An object of the present invention is to provide an electron beam exposure method that can easily and accurately correct differences in the positions of reference points when drawing needle patterns.

The feature of the present invention is that marks provided on the sample surface are scanned and detected by a minute beam near the first reference point and the second reference point of the second aperture. The purpose of this method is to obtain the amount of displacement of the projected position of the reference point, and use the amount of displacement when drawing an oblique pattern to correct the amount of deflection of the electron beam by the positioning deflector.

The present invention will be explained in detail below using examples.

FIG. 3 is a block diagram of essential parts of an embodiment of an electron beam exposure system used to carry out the present invention. In the figure, 21 is a central processing unit (CPU) of the computer, 22 is its storage device, 23 is an interface, 24 is a pattern data memory, 2
5 is a digital-to-analog converter (hereinafter abbreviated as DAC), 26 is a deflection amplifier, and 27 is a deflection correction amount △
a memory for storing x and △y; 28 is a selection circuit;
29 is an adder, 30 is a DAC, 31 is a deflection amplifier, 32 is a backscattered electron detector, 33 is an amplifier, 34
is a peak value detection circuit. Furthermore, 5 is the first aperture,
7 is a first deflection device (deflector), 8 is a second diaphragm, 9 and 10 are a reduction lens and a convergence lens, 1
1 is a second deflection device or positioning deflector, 1
Reference numeral 2 is a sample coated with resist, and there is no difference from the conventional one. Note that although the circuit portion in the figure is described only for the X-axis, the same circuit is also provided for the Y-axis.

Next, a method of drawing a diagonal pattern using the above electron beam exposure system will be explained.

When drawing a diagonal pattern, as mentioned above, the first reference point K and the second reference point of the second aperture 8 are
It is necessary to correct the difference in the position of K'. Therefore, first, the first deflection device 7 is activated, and the polygonal image 14 of the first aperture 5 and the second
An alignment mark provided on the surface of the sample 12 is scanned with a minute beam whose overlapped portion with the polygonal hole 15 of the diaphragm 8 is converged to a minute area near the first reference point K.

As shown in FIG. 3B, the alignment mark 35 is usually a recess formed on the surface of the sample 12, and when the alignment mark 35 is scanned with a minute electron beam 36, reflected electrons increase at the end 37. The amount of backscattered electrons is detected by the backscattered electron detector 32, amplified by the amplifier 33, and peak value detection circuit 34.
A peak is detected and a signal indicating the peak is sent to the CPU 21 via the interface 23.

Since this peak signal is emitted at both ends of the alignment mark 35, the CPU 21 calculates the coordinates of the center of the alignment mark from the coordinates of the position where the peak signal is emitted. The coordinates obtained in this way indicate the amount of deflection applied to the electron beam 36 by the second deflection device when the minute beam near the first reference point coincides with the center of the alignment mark.

Next, the first deflection device is activated to form a minute beam in the vicinity of the second reference point K' as shown in FIG. demand. These coordinates correspond to the amount of deflection applied to the electron beam 36 by the second deflection device when the minute beam near the second reference point K' coincides with the center of the alignment mark.

The CPU 21 is in the X-axis direction and Y-axis direction of the above two coordinates.
The axial differences Δx and Δy are calculated and sent to the memory 27 via the interface 23. The above △x and △y obtained in this way are the displacement amounts of the projection positions of the first and second reference points K and K' on the sample surface, and are the deflection when drawing the diagonal pattern. Used as a correction amount.

When drawing a diagonal pattern, in FIG. 3, a signal specifying the shape and size sent from the pattern data memory 24 based on a command from the CPU 21 is converted into an analog signal by the DAC 25 and amplified by the deflection amplifier 26. The polygonal image 14 of the first aperture 5 is applied to the first deflection device as shown in the figure.
An image is formed on the aperture 8.

On the other hand, the selection circuit 28 is activated by the diagonal pattern selection signal sent from the pattern data memory 24, and the memory 27 and the adder 29 are connected, and the deflection correction amount Δx and the position designation signal sent from the pattern data memory 24 are They are added by an adder 29.
The above position designation signal designates the coordinates of point E in the example of FIG. The position of the first reference point K is specified.

This added signal is converted into an analog signal by the DAC 30, amplified by the deflection amplifier 31, and applied to the second deflection device 11, thereby deflecting the electron beam having an oblique pattern cross section to a predetermined position.

As described above, the position of the diagonal pattern can be specified using the first reference point K, which is the reference point for specifying the position of the rectangular pattern.

The above-mentioned correction amount usually only needs to be determined once for each sample, and is accurate and easy. According to this embodiment, a diagonal pattern can be drawn as efficiently as a rectangular pattern.

Note that the second reference point is the point c in Figure 2 above.
It is not limited only to K', but is shown in Fig. 5a,
Each point indicated by K' in b and c can be used as appropriate depending on the pattern. When a plurality of second reference points are used, the amount of displacement with respect to the first reference point K may be determined for each of them as described above, and this may be used to correct the amount of deflection.

Further, the shape of the polygonal hole is not limited to the shape shown in the above embodiment, but may be any desired shape.

Furthermore, the system configuration for carrying out the present invention is not limited to the above-mentioned embodiments, and may be modified in various ways.

As explained above, according to the electron beam exposure method of the present invention, it is possible to specify the position of a diagonal pattern using the same reference point as that of a rectangular pattern, without requiring any complicated operations to change pattern data. Therefore, diagonal patterns can be accurately and easily drawn. In other words, by using the present invention, it becomes possible to effectively implement a variable shape electron beam exposure method.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of a variable-shape electron beam exposure apparatus, FIG. 2 is a diagram illustrating a method for exposing rectangular patterns and diagonal patterns, and FIG. 3 is a schematic diagram of an electron beam exposure system for carrying out the present invention. FIG. 4 is a block diagram showing a method of implementing the present invention, and FIG. 5 is a diagram showing a modification of the present invention. 5... First aperture, 6... Electronic lens, 7... First deflection device, 8... Second aperture, 9... Reduction lens, 10... Converging lens, 11... Second deflection device, 12... Sample, 13... Polygonal beam after passing through the first aperture, 14, 14'... Image of 13, 15,
15'...Polygonal hole of second aperture, 16,16'...
Electron beam after passing through the second aperture, 17, 17'...
Patterns printed on the sample, 18... Rectangular pattern, 19... Diagonal pattern, 21...
CPU, 24...Pattern data memory, 27...
...memory, 28...selection circuit, 29...adder,
30...DAC, 32......backscattered electron detector, 3
4... Peak value detection circuit, 35... Alignment mark, 36... Electron beam, 37... End, A...
Projection of the first reference point, E...projection of the second reference point, K...the first reference point, K'...the second reference point.

Claims (1)

[Claims] 1. A first aperture having a polygonal hole that shapes the cross-sectional shape of the electron beam into a predetermined polygon, and a second aperture having a polygonal hole arranged so as to be able to partially shield the shaped electron beam. A first deflection device that deflects the transmitted beam of the first aperture to a predetermined position on the second aperture, and a second deflection device that deflects the transmitted beam of the second aperture to a predetermined position on the sample surface. An electron beam exposure device is used to produce two sets of electron beams parallel to the two deflection axes of the electron beam, the X axis and the Y axis, respectively.
In an electron beam exposure method for drawing a rectangular pattern consisting of sides and a diagonal pattern in which at least two sides obliquely intersect with the X-axis and the Y-axis, a projected image of a second aperture of the four sides of the rectangular pattern is One corner of the second diaphragm corresponding to the intersection of two sides is set as the first reference point, and one corner of the second diaphragm corresponding to the intersection of two sides that is a projected image of the second diaphragm among the four sides of the diagonal pattern. is set as a second reference point, and marks provided on the sample surface are scanned by a second deflection device using a minute beam in the vicinity of the first reference point and the second reference point, respectively. The amount of deflection of the electron beam by the second deflection device when the position is detected is known, and the difference between the two deflection amounts is determined. When drawing the diagonal pattern, the projection position of the second reference point is determined. By specifying the coordinates whose coordinates have been corrected by the difference as the coordinates of the projection position of the first reference point, a rectangular beam parallel to the deflection axes X and Y axes and a beam oblique to the X and Y axes can be formed. An electron beam exposure method characterized by aligning the relative positions of exposed patterns.