JPH01297823A - Exposure with electron beam - Google Patents

Abstract

PURPOSE:To reduce lowering of the accuracy of a pattern at an interface by exposing to an electron beam a figure in virtual sub-field region and a figure on and out of the virtual sub-field region without division of the former figure but with division of the latter figure at the interface between the sub-field regions. CONSTITUTION:Respective basic figures in a field region 16 are divided into sub-field regions 21a, 21b, 21c and 21d. For the figures 21b, a basic figure 19a in a figure 19 composed of the basic figures 19a, 19b is existent in a virtual sub-field region composed of a margin region 22 and the region 21b without protruding from the same region, while the figure 20 protrudes also into the marginal region 22. The figure 19a is exposed to an electron beam as a figure within the region 21b, and thereafter the figure 20 is divided at an interface between the regions 21b and 21c and the figure 20a is exposed to an electron beam as a figure within the region 20b. Thus, accuracy of a pattern at the interface can be prevented from being lowered.

Description

[Detailed Description of the Invention] [Summary] Regarding an electron beam exposure method that draws a pattern in units of subfield regions, the present invention aims to reduce deterioration in pattern accuracy at boundaries between adjacent subfield regions (including field boundaries). The basic figure obtained by dividing the pattern to be drawn is divided into field area and subfield area figures, and then an electron beam is applied to the sample surface based on the exposure data registered as figure data for each subfield area. In the electron beam exposure method for forming the pattern to be drawn as described above, a margin area is virtually provided in advance around the main field area, including the subfield area, in which the electron beam can be deflected and scanned; inspection means for inspecting whether a figure protruding from the margin exists within a virtual subfield area including the margin area without protruding; and a figure within the virtual subfield area obtained by inspection by the inspection means. The figure includes at least an overflow processing means for registering the figure as the exposure data without dividing it, and dividing the figure that extends beyond the virtual subfield area at the boundary of the subfield area and registering the figure as the exposure data. Configure it like this.

[Industrial application field]

The present invention relates to an electron beam exposure method, and more particularly to an electron beam exposure method for drawing a pattern in subfield units.

In an electron beam exposure device, there is an area (field area) of several millimeters square where the exposure equipment can deflect the electron beam, and a field area of several hundreds of μm where the electron beam is deflected within the field area to improve viscosity. An electron beam exposure apparatus is known that draws a pattern in units of nubno yields, which are divided into corner Kozonomukai areas (subfield areas).

FIG. 3 is a diagram of an example of the optical system of this type of electron beam exposure device 6. In the figure, the electron beam emitted from the electron gun 1 passes through the aperture 2 and is shaped into a rectangular beam by the beam shaping section 3. It can be molded to any size by Surin [-4. This rectangular beam passes through a reduction unit 5 consisting of a reduction lens and is directed to a focusing/deflection unit 6, where it receives each deflection in the field area and subfield area, and then onto the surface of a wafer 7 as a sample. It is irradiated to draw a pattern.

The drawing pattern on the wafer 7 described above is formed by restricting the deflection amount of the focusing/deflecting unit 6 based on exposure data registered in advance, so the exposure data is generated so as to obtain a highly accurate pattern. That is important.

[Conventional technology]

FIG. 4 shows a flowchart of an example of a conventional electron beam exposure method. As shown in the figure, conventionally, in order to generate the exposure data, first CAD (Computer A
Step 511) Extract only the figures necessary for drawing from the design data created with ided Desic+n) etc. and develop them on the chip Step 511) Remove complexly overlapping figure parts from the developed figures Step 5I2) The basic shapes (rectangles, triangles,
(parallelogram, 2 trapezoids, etc.) (step 513)
.

Next, the basic figure is divided into a field area and a subfield area (step 514), and the subfield data is registered as exposure data (step 515).

As a result, as shown in FIG. 5(A), if there are figures 11, 12 and 13 in the field area 10, step S
As a result of the subfield area division process' at 14, the subfield area is divided into four subfield areas, for example, as shown at 148.about.14d in FIG. Data (subfield data) related to figures in these subfield areas 14a to 14d are registered and used for subsequent actual exposure.

[Problem to be solved by the invention]

In this way, exposure data is registered as figure data in the middle of the subfield area, but conventionally, boundaries between adjacent subfield areas have not been taken into account, so figures are simply divided at the boundaries of subfield areas. Then, since the connection accuracy between the V field regions is usually about 0.1 μm, minute figures may occur near the boundaries of the V field regions.

For this reason, in the past, the patterns sometimes separated or overlapped at the boundaries of subfield regions due to these minute figures, which was one of the causes of deterioration in pattern accuracy.

The present invention has been made in view of the above points, and it is an object of the present invention to provide an electron beam exposure method that can reduce pattern accuracy at boundaries between adjacent subfield regions (including field boundaries). purpose.

[Means to solve the problem]

In the electron beam exposure method of the present invention, a margin area is virtually provided in advance around a subfield area, including the subfield area, in which the electron beam can be deflected and scanned, and a figure protruding from the subfield area includes the margin area. Inspection means for inspecting whether or not shapes exist within the virtual subfield area without protruding, and shapes within the virtual subfield area are registered as exposure data without being divided, and the virtual subfield area also extends beyond the virtual subfield area. The figure has at least an overflow processing means that divides the figure at the boundary of the subfield area and registers the divided figure as exposure data.

[Effect]

A figure that slightly protrudes into the subfield area exists without protruding into the above-mentioned virtual subfield area. Here, the subfield area is determined based on the hardware constraints of the device, but this subfield area is not the maximum subfield range in which the electron beam can be scanned and deflected, but is larger than this by taking into account distortion etc. It is set in a small area.

Therefore, in the present invention, in view of the above points, a virtual subfield area is provided that is the maximum subfield range or slightly narrower than the maximum subfield range, but wider than the subfield area, and the above-mentioned overflow processing means is used to provide a virtual subfield area that extends outside the υ field area. Graphics that slightly protrude into the subfield area, such as those that exist without protruding into the subfield area, are registered as exposure data of the subfield area without being divided.

= 7 - Therefore, when a pattern is drawn based on this exposure data, the graphic pattern is drawn extending beyond the subfield area during exposure of the subfield area, and is not divided at the boundary of the subfield area. .

On the other hand, a figure that protrudes from the virtual subfield area is divided by the protrusion processing means at the boundary of the original subfield area and registered as exposure data.

This is because when dividing at the boundary of a virtual subfield area, there is a possibility that a new minute figure will be generated near the boundary. This reduces the occurrence of minute figures at the boundary between adjacent subfield regions.

〔Example〕

FIG. 1 shows a flowchart of an embodiment of the electron beam exposure method according to the present invention. In the figure, steps 81 to S3 are the same as steps So to Sea in the conventional method.

That is, only the figures necessary for drawing are developed on the chip by the development process in step S1. FIG. 2(A) shows an example of the field area 16 consisting of this developed figure. In Figure 2 (A), figures 17 to 2o are figures expanded from the set 1 data, and figures 18 and 19 are! pI
There is ejaculation.

Next, by the overlap removal process of step S2 in FIG. 1, the overlap of figures 1.8.19 is removed, and then step S3
By the basic figure dividing process, each figure 17-20 is divided into the basic figures of the tongue shape as shown in FIG. 2(B).

Next, in this embodiment, the basic figure is placed in the field area.

The area of each basic figure is determined by dividing it into subfield areas (step S4 in FIG. 1). This results in
As shown in FIG. 2(A), each basic figure in the field area 16 is divided into subfield areas 21a, 21b, 21c.
and 21d, respectively. Although the subfield regions 21a to 21d are normally square, they are shown as elongated in FIG. 2 for convenience of illustration.

Next, it is determined whether each basic figure is completely included in each of the subfield areas 21a to 21d, and if it is completely included (figures 17 and 18 in FIG. 2(B)), step S8, which will be described later. Processing is performed, and figures that are not completely included (19 and 20 in FIG. 2(B)) are inspected for protrusion (step 86 in FIG. 1).

This protrusion inspection processing step S6 performed by the computer corresponds to the protrusion inspection means, and it is inspected whether the basic figure is included in a margin area that is virtually provided around the subfield area in advance.

That is, as shown in FIG. 2(C), a margin area 22 is virtually provided around the subfield area 21b. In this margin region 22, the maximum range of the small deflection region in which the electron beam can be deflected and scanned by the sub-deflector is, for example, 102.4 μm square, and each of the subfield regions 21a to 21d is set to be, for example, 100 μm square, taking into account the margin. For example, the width is set to 05 μm. Therefore, the electron beam can deflect and scan both the margin area 22 and the subfield area 21b during one pattern drawing.

As a result of the above protrusion inspection, the leave field area 21
Figure 2 and 20 protruding from b are shown in Figure 2 (C)
In the figure 19 consisting of the basic figures 19a and 19b, it is determined that the basic figure 19a exists without protruding into the virtual subfield area consisting of the margin area 1iA22 and the subfield area 1fi21b,
In addition, it is determined that the figure 20 extends beyond the margin area 22.

Next, in step S7 of FIG. 1, the basic figure 19a in the virtual subfield area is processed as a figure in the subfield area 2Ib by the protrusion process, and then in step S8, the figure that protrudes from the virtual subfield area is processed. 20 is divided at the boundary between subfield areas 21b and 21c, and the basic figure 20a is divided into subfield areas 21b.
Let the figure be .

Therefore, the basic figure 19a indicated by diagonal lines in FIG. 2(C),
19b and 20a are used as graphic data of the subfield area 21b, and are registered as subfield data of the subfield area 21b in the next step S9. The above steps 87 to S9 correspond to the above-mentioned protrusion processing means.

Thereafter, all the figures on the chip are processed in the same manner as above. In addition, basic figure 1 in Fig. 2 (C)
'9a has been registered as subfield data in the subfield area 21b, so when subfield data registration processing is subsequently performed in the subfield area 21C, it is treated as not existing in the subfield area 21c. . This prevents the same basic figure from being exposed overlappingly.

The subfield data registered in this way is then applied as exposure data to the focusing/deflecting unit 6, and the electron beam is scanned by a predetermined amount in a predetermined direction to perform actual exposure. is 10
Exposure is performed using the original subfield area of 0 μm square.

However, the subfield "area 2" shown in FIG. 2(C)
1b, the exposure data includes the 7-gin area 22.
Since the data of the basic figure 19a within is also included, the device draws the basic figure 19a without dividing it. On the other hand, when exposing the field area 21c, data for the basic figure 20b exists in the exposure data, but the basic figure 19a
Since no data exists, the device draws the basic figure 20b.

〔Effect of the invention〕

As described above, according to the present invention, the subfield area is virtually enlarged, pattern division is determined at the subfield area boundary (including the field boundary), and minute figures are generated at the subfield area boundary. This makes it possible to significantly reduce phenomena such as patterns separating or overlapping at adjacent subfield boundaries compared to conventional methods, and improve pattern drawing accuracy at subfield boundaries. It has features such as:

[Brief explanation of the drawing]

FIG. 1 is a diagram of an embodiment of the present invention, FIG. 2 is an explanatory diagram of an embodiment of exposure data generation according to the method of the present invention, and FIG. 3 is an illustration of an electron beam exposure apparatus. 4 is a flowchart showing an example of a conventional method, and FIG. 5 is an explanatory diagram of exposure data generation according to the conventional method. In the figure, 16 is a field area, 17 to 20 21a to 21d are figures, 21a to 21d are subfield areas, 22 is a margin area, S6 is an outflow inspection processing step, S7 is an outflow processing step, S8 is a field, a subfield area division processing step, and S9 is a registration step.Patent applicant Fujitsu Ltd.

Claims (1)

[Claims] A basic figure obtained by dividing a pattern to be drawn is divided into a field area (16) and subfield areas (21a to 21).
In the electron beam exposure method of d), the pattern to be drawn is formed on the sample surface by an electron beam based on exposure data that is divided into figures (17 to 20) and registered as figure data for each subfield region, A margin area (22) is virtually provided in advance around the subfield areas (21a to 21d), including the subfield areas (21a to 21d), in which the electron beam can be deflected and scanned. 21d)
an inspection means (S_6) for inspecting whether a figure protruding from the margin exists within a virtual subfield area including the margin area without protruding; and the virtual image obtained by inspection by the inspection means (S_6). Figures within the virtual subfield area are registered as the exposure data without being divided, and figures that extend beyond the virtual subfield area are registered as the exposure data in the subfield area (21
an electron beam exposure method comprising at least the following: a protrusion processing means (S_7 to S_9) for dividing a figure at the boundaries of a to 21d) and registering the divided figures as the exposure data.