KR100214266B1 - Cell aperture used in e-beam lithography - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cell aperture applied to electro-beam lithography in the manufacture of semiconductor devices. In the cell aperture used for the E-beam lithography in which the pattern used for exposure is opened, a plurality of dummy patterns having a smaller size than the size of the VSB pattern are provided next to the VSB pattern.

Description

Cell Aperture Applied to E-Beam Lithography

1 is a plan view showing cell apertures applied to conventional E-Beam lithography.

FIG. 2 is a plan view showing cell apertures applied to E-Beam lithography produced by the present invention. FIG.

* Explanation of symbols for main parts of the drawings

1: contact pattern 2: wiring pattern

3: silicon substrate 10: pattern for VSB

15: dummy pattern 20, 30: cell aperture

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to cell apertures applied to electro-beam lithography in the manufacture of semiconductor devices.

The cell aperture currently in use in cell projection E-beam lithography uses a 125 μm × 125 μm square pattern for a Variable Shaped Beam (VSB) located in the center of the mask. That is, the alignment correction is performed by comparing the difference between the previously stored pattern shape and the image transmitted through the VSB pattern after cell mask loading.

However, in the situation where the reduction ratio of the E-beam lithography is 25: 1, the minimum pattern of 125 mm × 125 μm square pattern for VSB is scanned on the wafer with the size of the 5 μm × 5 μm square pattern because the pattern size is too large. More than 256M devices with sizes down to 0.25µm require more precise control of mask alignment.

1 shows a plan view of a cell aperture 20 used in a conventional cell mask alignment.

Referring to the drawings, of the five patterns open on the silicon substrate 3, the upper two and the lower two are patterns used for cell area exposure, for example, the contact pattern 1 and the wiring pattern 2 ), And the square pattern located at the center portion is a VSB pattern 10 having a 125 µm x 125 µm square pattern used for mask alignment.

When the cell mask is loaded during exposure, the mask aligns immediately. In this case, the difference between the VSB pattern previously stored according to the equipment and the newly formed VSB pattern after exposure is divided into signal differences using the principle of SEM. Analyze the alignment correction.

However, since the size of the pattern for VSB exposed by reduction becomes 5 micrometers x 5 micrometers, there exists a problem that an accurate misalignment is not measured.

Accordingly, the present invention provides a cell aperture for precisely aligning a cell mask by providing a dummy pattern having a fine size in order to improve alignment accuracy in addition to the VSB pattern used for mask alignment in the cell aperture. There is a purpose.

The present invention for achieving the above object is used in E-beam lithography in which a VSB pattern is opened in a square at a central portion of a silicon substrate, and a pattern used for cell area exposure is opened at an edge of the VSB pattern. In the cell aperture, the plurality of dummy patterns having a smaller size than the size of the VSB pattern are provided next to the VSB pattern.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

2 shows a plan view of a cell aperture 30 made in accordance with the present invention.

Referring to the drawings, of the five patterns opened on the silicon substrate 1, the upper two and the lower two are patterns used for cell area exposure, for example, the contact pattern 1 and the wiring pattern 2 ), And the square pattern located at the center portion is a VSB pattern 10 having a 125 µm x 125 µm square pattern used for mask alignment.

In order to align the mask more accurately during exposure, a plurality of dummy patterns 15 having a size of 5 μm × 5 μm are provided on the X-axis and the Y-axis beside the VSB pattern 10.

The dummy pattern 15 may be formed in a square, a rectangle, or a polygon. The dummy pattern 15 may be arranged to be separated by a predetermined interval on the X and Y axes, and may be maintained at a predetermined angle.

In FIG. 2, the Y-axis alignment correction is performed by comparing 1, 2, 3, and 4 of the dummy pattern 1, and the X-axis alignment correction is performed by comparing 1, 3, 2, and 4.

That is, in the case of Y-axis alignment correction, the judgment is based on whether two patterns (1 and 2 or 3 and 4) are correctly aligned in the center portion in the X-axis direction, and in the case of X-axis alignment correction, the dummy pattern 15 As a reference for the horizontal correction, an image generated after shifting 1 and 2 of 5 by 5 mu m downward becomes a rectangle of 0.8 mu m x 0.2 mu m. If exposed as designed, the left side of the top pattern and the right side of the bottom pattern are exactly the same rectangle when shifted.

It is possible to accurately implement the desired pattern by improving the cell mask alignment alignment accuracy.

Claims (4)

In the cell aperture used for E-beam lithography in which a VSB pattern is opened in a square at a central portion of a silicon substrate, and a pattern used for cell area exposure is opened at an edge of the VSB pattern, wherein the VSB pattern A cell aperture applied to E-Beam lithography, wherein a plurality of dummy patterns having a smaller size than the size of the VSB pattern are provided next to each other. The cell aperture of claim 1, wherein the dummy pattern has a size of about 5 μm × 5 μm. 2. The cell aperture of claim 1, wherein the dummy pattern is provided in plural, with a plurality of dummy patterns spaced apart at predetermined intervals from each of the X-axis and the Y-axis. The cell aperture of claim 1, wherein the dummy pattern is provided in a square, rectangular, or polygonal shape.