JPH03188617A - Method for electron beam writing - Google Patents

Abstract

PURPOSE:To average an error produced in connection with the movement of a sample so as to draw a picture with high accuracy of pattern position by superimposing X- and Y-direction stripe-like picture drawing patterns upon another. CONSTITUTION:When picture drawing stripes are drawn with an electron beam by moving a sample in Y-direction, etc., highly accurate picture drawing patterns 11a-14a are drawn in the Y-direction, since the stripes are continuously drawn in the Y-direction. Similarly, highly accurate picture drawing patterns 11b-14b are drawn in X-direction which is normal to the Y-direction by drawing stripes in the X-direction after moving the sample to the X-direction. When the patterns 11a-14a and 11b-14b which correspond to each other are respectively superim posed upon another, the error produced in connection with the movement of the sample is averaged and picture drawing patterns 11c-14c are obtained with high positional accuracy.

Description

[Detailed description of the invention] Industrial applications The present invention relates to an electron beam writing method.

There are two types of conventional electron beam lithography methods, a step-and-repeat method and a continuous movement method, depending on how the sample stage is moved.

The step-and-repeat method, for example, connects drawing areas while repeating step movements in the X direction,
One step movement is made in the Y direction at the end of the sample, and then the step movement is repeated in the -X direction. When the end of the sample is reached, one step movement is performed in the Y direction. Repeat the above operations to draw the entire surface of the sample.

In the continuous movement method, for example, a stripe-shaped area of a constant width is drawn while continuously moving the sample stage in the X direction, and when it reaches the end of the sample, step movement is performed in the Y direction. Then -
Continuously moves in the X direction. Repeat the above operations to draw the entire surface of the sample.

In either method, the overall drawing operation involves dividing the sample into long stripe-like regions in the X direction, and connecting these regions to perform the entire drawing.

In order to improve drawing accuracy, it is important for both drawing methods to prevent accuracy deterioration due to step movement of the sample stage. From this point of view, an attempt has been proposed in which stripes are overlapped by making the step movement amount smaller than the stripe width, thereby achieving higher precision by performing multiple drawing.

Problems to be Solved by the Invention In such conventional electron beam lithography methods, lithography in the X direction is temporally continuous, but lithography in the Y direction is not necessarily continuous, and Various error factors occur at the joints in the Y direction, such as misalignment with the sample and expansion due to changes in sample temperature during drawing, so it is difficult to improve accuracy without increasing the number of times the striped drawing areas are overlapped. Therefore, there was a problem that the drawing time became significantly longer and the throughput decreased.

Means for Solving the Problems In order to solve these problems, the electron beam drawing method of the present invention overlaps stripe drawing in the X direction and stripe drawing in the Y direction.

Effect: With this method, it is possible to provide temporal continuity to drawing in the Y direction, and highly accurate drawing can be achieved with a small number of superimpositions.

Embodiment FIGS. 1A and 1B are drawing pattern diagrams for explaining an embodiment of the electron beam drawing method of the present invention.

In this embodiment, the sample movement method is a continuous movement method, and the number of times of superimposition is two in total, once in each of the X and Y directions.

Figure 1 fat, (In each figure of bl, 1 is the sample, 2
．． 3 is a drawing pattern, and 4 to 9 are striped drawing areas.

The first drawing is performed by connecting the striped drawing areas in the Y direction as shown in FIG. draw.

When the end of the sample is reached, a step movement is performed in the X direction (arrow AI), and then the stripe 5 is drawn while continuously moving the sample in the Y direction (arrow B2). Thereafter, the same operation is repeated to draw the entire surface of the sample.

The second drawing is performed by connecting the striped drawing areas in the X direction as shown in FIG. Make a movement by swapping X and Y with 1 drawing.In this way, draw the entire surface of the sample.

Each drawing is performed with an exposure amount that is 1/2 of the optimum exposure amount for the electron beam resist used. Therefore, the pattern to be resolved will be a portion where each drawing overlaps, and the positional accuracy will be high. The situation will be explained using FIG. 2.

In FIG. 2, 113 to 14a represent patterns drawn in the first drawing, 11b to 14b represent patterns drawn in the second drawing, and 110 to 14c represent patterns to be resolved.

The patterns 11a to 14a drawn by the first drawing are
Since the drawing is performed temporally continuously in the Y direction, the positional accuracy in the Y direction is extremely high, but the positional accuracy in the X direction is slightly inferior. On the other hand, the pattern llb~ drawn by the second drawing
14b has high positional accuracy in the X direction, but is slightly inferior in the Y direction.

Therefore, the overlapping portions 11c to 14c of both are resolved, but the positional error of both is averaged and becomes 1/2. Compared to the case where only stripes in the same direction are superimposed, in the present invention, since a highly accurate drawing pattern in the X direction and a highly accurate pattern in the Y direction are superimposed, the degree of improvement in positional errors is extremely large.

It should be noted that even in the step-and-repeat method, a large accuracy improvement can be obtained in exactly the same way.

In addition, in each drawing, if the step movement amount connecting the striped drawing areas is made smaller than the stripe width and the conventional method of overlapping stripes in the same direction is also carried out, an even greater improvement in precision can be obtained.

Effects of the Invention According to the electron beam writing method of the present invention, by averaging errors caused by sample movement, writing with high pattern position accuracy is possible.

[Brief explanation of drawings]

FIG. 1 is a drawing pattern diagram showing an electron beam drawing method in one embodiment of the present invention, and FIG. 2 is a plan view showing a drawing pattern in one embodiment. 1...Sample, 1la-14a...1st
Drawing patterns, 11b to 14b... second drawing patterns, 11c to 14c... resolution patterns.

Claims (1)

[Claims] An electron beam lithography method characterized by stacking a plurality of lithography images rotated at an arbitrary angle in relation to sample movement accompanying electron beam lithography.