KR100273294B1 - Mark formation structure for focus management of semiconductor mask - Google Patents

Abstract

PURPOSE: A mark formation structure for managing a focus of a semiconductor mask is provided to determine an optimizing focus by using a mechanical method to measure measuring pattern. CONSTITUTION: A multitude of measuring pattern(11) having different long axis width(L) is arranged on a predetermined portion of a mask. An exposure process is performed according to a distance of a wafer by using the mask formed with the measuring patterns. A measuring pattern is selected from the exposed measuring patterns(11). A long axis width of the selected measuring pattern is measured. A graph is described by using the measured long axis width. A fixed point is confirmed on the basis of the described graph.

Description

Mark formation structure for focus management of semiconductor mask

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mark forming structure for focus management of a semiconductor mask. In particular, a mark for focus management of a semiconductor mask suitable for allowing a worker to easily determine an optimal focus by measuring and drawing a measurement pattern by a mechanical method. It relates to the formation structure.

In general, an exposure apparatus for implanting a circuit onto a semiconductor wafer forms a focus management mark on a specific mask for focus management, and performs exposure while moving the wafer position while the mask on which the focus management mark is formed is fixed. The exposure for focus management is performed periodically or when focus management is required.

1 is a plan view showing a state in which a mark for focus management is formed on a mask in the related art. As shown in the drawing, a mark 1 is formed at a predetermined portion of the mask, and the mark 1 has a plurality of marks. The hole pattern 3 in which the holes 2 are formed is formed on the left and right sides, and the line and space pattern 5 in which several lines 4 are formed at regular intervals on both sides of the hole pattern 3 is formed. It is formed in the form which is formed, and is each 0.3 micrometer-1.0 micrometer in size.

In the state where the mask 6 having the mark 1 as described above is positioned above the lens 7 as shown in FIG. 2, the wafer is exposed to the wafer several times so that the distance between the wafer and the lens 7 is different. After the exposure is performed, the exposed wafer is placed on a microscope, and the operator finds a state in which the minimum hole pattern 3 is formed, determines it as an optimal focus (best focus), and adjusts the equipment to perform mass production.

However, in the structure for forming the mark 1 for focus management of the conventional semiconductor mask as described above, since the operator observes the exposed wafer directly under a microscope to determine the optimum focus state, measurement errors for each operator may occur, and therefore, accurate focusing. There was a problem that can not manage.

SUMMARY OF THE INVENTION An object of the present invention devised in view of the above problems is to provide a mark forming structure for focus management of a semiconductor mask suitable for enabling accurate focus management of an exposure apparatus by mechanical measurement.

1 is a plan view showing a mark forming structure for focus management of a conventional mask;

Figure 2 is a state diagram for explaining a state of managing the focus of the conventional exposure equipment.

3 is a plan view showing a mark management structure for focus management of the semiconductor mask of the present invention;

4 is a graph showing a change in the long axis width of the mark for focus management of the present invention;

Explanation of symbols on the main parts of the drawings

11: measurement pattern 11a: area

11b: corner

In order to achieve the above object of the present invention, in forming a pattern on a mask for focus measurement, a semiconductor mask comprising a plurality of measurement patterns having different long-axis widths arranged in a predetermined portion of the mask. A mark forming structure for focus management is provided.

Hereinafter, the mark forming structure for focus management of the semiconductor mask according to the present invention configured as described above will be described in more detail with reference to embodiments of the accompanying drawings.

3 is a plan view showing a mark management structure for focus management of the semiconductor mask of the present invention. As shown, the focus management mark formation structure of the semiconductor mask of the present invention has a plurality of different long axis widths L at predetermined portions of the mask. The measurement patterns 11 are arranged in series.

The measurement pattern 11 has a rhombic shape in which sharp edges 11b are integrally formed at both ends of an area portion 11a of a predetermined size, and the major axis width L is 0.5 μ, 1 μ, 2 μ, 3 μ, 4 μ, 5μ, 8.5μ, and 10μ are each different in size.

The focus measuring mask, in which the rhombic measurement patterns 11 having the different long-axis widths L, are formed, is mounted on the exposure apparatus, and the distance from the lens is different while the wafer is placed on the stage. Then, the measurement patterns 11 of the mask are exposed on the wafer. When the exposure is performed in this manner, the measurement patterns 11 of the mask are exposed on the wafer. At this time, one measurement pattern 11 is determined to mechanically measure the size of the wafer as the optimal focus by observing the position of the wafer that appears most clearly as shown in FIG. Optimum focus is determined by drawing the same change graph of the long axis width (L).

That is, the operator is clearly exposed to the edge portion 11b of the selected measurement pattern 11 as shown in FIG. 4 so that the size of the long axis width L is exactly the vertex 13 of the graph 12. This point is judged to be optimal focus.

As described in detail above, the focus management mark formation structure of the semiconductor mask of the present invention forms a plurality of measurement patterns having different long-axis widths on a predetermined portion of the mask, and uses a mask on which the measurement patterns are formed to form a distance to the wafer. After each exposure, the long-axis width of the selected measurement pattern among the measurement patterns exposed on the wafer is measured mechanically so that the graph is drawn, so that the operator can determine the optimal focus accurately by checking the peak of the graph. Therefore, accurate focus management is possible.

Claims (2)

A pattern forming structure for focus management of a semiconductor mask, wherein a pattern is formed in a mask for focus measurement, wherein a plurality of measurement patterns having different long-axis widths are arranged in a predetermined portion of the mask. The method of claim 1, wherein the measurement pattern has a rhombic shape in which sharp edges are integrally formed at both ends of an area portion of a predetermined size, and the major axis width (L) is 0.5 µ, 1 µ, 2 µ, 3 µ, 4 µ, 5 µ, or 8.5 µ. A mark forming structure for focus management of a semiconductor mask, wherein the size of each of the micro masks is 10 µm.