JPH02265236A - Drawing by charged particle beam - Google Patents

Abstract

PURPOSE:To enhance a fine processing accuracy by eliminating a difference in level at a boundary line of fields by a method wherein, when adjacent fields are drawn inside a marginal area, mutually supplementary doses are given and their total is made equal to a desired doe. CONSTITUTION:When a drawing operation by a charged particle beam of a vector scanning system is executed on a specimen, the charged particle beam is deflected to a desired position and a stage on which the specimen has been mounted is moved in a step-and-repeat manner. During the operation, margin areas 4 of a region which has definite widths Mx, My at the inside of a field 2 as a region which can be drawn without moving the stage from an outer periphery of the field 2 are formed. When adjacent fields A, B are drawn, mutually supplementary doses DA, DB are given while the doses DA, DB are being increased gradually from an outer periphery of the individual marginal areas 4 toward the inside at the individual fields A, B in such a way that the total of the individual doses DA, DB becomes a desired dose. Thereby, the difference in level of patterns at a boundary of the fields is eliminated; and a fine processing accuracy can be enhanced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a charged beam drawing method, and particularly to microfabrication technology in semiconductor manufacturing.

[Conventional technology]

Conventionally, this type of charged beam writing method involves writing one field at a constant desired dose N (Dosage), then moving the stage by the field size and writing the next field. By repeating this process, a desired pattern can be drawn.

FIG. 5 is a plan view showing an example of a conventional drawing pattern. In this case, a pattern 1 to be drawn is shown arranged across a plurality of fields 2.

[Problem to be solved by the invention]

In the conventional charged beam writing method described above, due to the effects of distortion in the beam deflector, errors in the stage position, space charge effects specific to charged beams, etc., at the field boundary between fields 2, as shown in FIG. As shown, in the connection diagram between field A and field B of pattern 1, there is a problem in that a local level difference occurs between area pattern 15 of field A and area pattern 16 of field B with boundary line 14 in between.

In order to reduce such level differences, a method is sometimes used in which a method is used to correct the deflection distortion of the charged beam and write while performing the correction, but the correction technique is difficult;
Furthermore, it is impossible to completely eliminate the level difference. Also,
This level difference at the field boundary is a major factor in reducing the precision of microfabrication.

The purpose of the present invention is to solve such problems by providing a margin area with a certain width from the outer periphery of the field to the inside, and applying complementary doses to each other when drawing adjacent fields within this margin area. It is an object of the present invention to provide a charged beam lithography method which can eliminate steps in field boundary lines and improve microfabrication accuracy by making the total amount equal to a desired dose amount.

[Means to solve the problem]

The present invention provides a vector scanning charged beam drawing method in which drawing is performed on a sample by deflecting a charged beam to a desired position and moving a stage on which a sample is placed in a step-repeat manner. In addition, a margin area with a certain width is provided inside the field from the outer periphery of the field that can be drawn, and when drawing adjacent fields, each field has a margin area from the outer periphery of each margin area. It is characterized in that the doses are given complementary to each other while gradually increasing toward the inside, so that the sum of these doses becomes the desired dose.

〔Example〕

Next, the present invention will be explained with reference to the drawings.

FIGS. 1(a) and (b) are plan views of the vicinity of the field area boundaries and graphs showing the dose amount of each area for explaining one embodiment of the present invention, and FIG. 2 is a graph showing the drawing area of FIG. 1. FIG. In FIG. 2, field 2 is composed of a rectangle (FXxFy) with a field size of FX, Fy (7) in width, and drawing is performed in each field by deflecting a charged beam while the stage is stopped. A margin area 4 having a width MX in the X direction and a width Mv in the Y direction is provided at the outer periphery of each field 2 of each drawing pattern 1.

Within the margin area 4 of each pattern 1, a dose amount that gradually increases from the outer periphery toward the inside is applied.
A 100% dose is applied to the external pattern area. After drawing one field 2, move the stage in the X direction to F, -MX, and again in the X direction to Fy.
After moving by -My and stopping the stage, drawing in field 2 is performed according to the above-described method, and the above process is repeated to draw desired pattern 1.

This means that as shown in Figure 1 (a), which is an enlarged version of Figure 2,
A 100% dose is applied to pattern areas 11.12 other than the margin area 4 of fields A and B, as shown in FIG. 1(b). This margin area 4
From the outer periphery of the field toward the inside,
) As shown in the graph, a dose that increases linearly from 0% to 100% is given, and the sum of the dose DA within the field and the dose DB given from field B becomes 100%. I'm doing it like that.

FIG. 3 is a plan view of the pattern obtained in this example. Field A according to this embodiment.

This shows that the pattern 13 in B can be connected linearly without a step difference because of the margin area 4, and the step difference at the field boundary is linearly absorbed by the margin area 4.

Note that the setting of the margin area 4 may be performed on the pattern data format or may be performed by the data processing section of the drawing device.

FIG. 4 is a plan view when drawing is performed to explain the second embodiment of the present invention. In this embodiment, a pattern edge margin area 13 is set at the edge of the desired pattern (here, the width in the X direction is MX□, and the width in the y direction is My2). Complementary exposure using adjacent fields is performed only on the overlapping portion of pattern edge margin area 13 and margin area 4, and the other portions are exposed using a conventional method.

In this case, the area for complementary exposure can be made smaller, and the exposure time can be shortened compared to the first embodiment.

Note that the pattern edge margin area may be set on the pattern data format, or may be set in the drawing device data processing section.

〔Effect of the invention〕

As explained above, the present invention provides a margin area with a certain width inward from the outer periphery of the field, and within this margin area, mutually complementary doses are given by drawing adjacent fields. By gradually increasing the dose from the outer periphery toward the inside until the total dose is equal to the desired dose, it is possible to eliminate pattern steps at field boundaries and improve microfabrication accuracy. effective.

[Brief explanation of drawings]

FIGS. 1(a) and (b) are plan views of the field area for explaining the present invention in detail and characteristic diagrams for explaining the dose amount of each area. FIG. 2 is a plan view for explaining the drawing area of FIG. 1. , FIG. 3 is a plan view near the field boundary of the drawing obtained by the embodiment of FIG. 1, FIG. 4 is a plan view of the drawing pattern of the second embodiment of the present invention, and FIG. FIG. 6 is a plan view of the drawing pattern shown in FIG. 5 near the field boundary. 1...Drawing pattern, 2...Field, 4...
Margin area, 11.12...Field area,
13...Pattern edge/margin area, 14...
・Field boundary line, 15.16... Area pattern, DA, DB... Dose amount, FX, Fy... Field size, MX, My, MX□1My□... Margin area, Fuku.

Claims (1)

[Claims] In a vector scanning charged beam drawing method in which drawing is performed on a sample by deflecting a charged beam to a desired position and moving a stage on which a sample is placed in a step-repeat manner, drawing can be performed without moving the stage. A margin area with a certain width is provided from the outer periphery of the field to the inside of this field, and when drawing adjacent fields, the dose amount is set inward from the outer periphery of each margin area in each field. A charged beam lithography method characterized in that the doses are given in a mutually complementary manner while gradually increasing the amounts, so that the sum of these doses becomes a desired dose.