KR0144084B1 - Formation method of alignment measuring mark - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a method for forming alignment measurement marks for measuring the accuracy of pattern overlap between layers in a lithography process for forming a pattern forming a device in a semiconductor and liquid crystal display (LCD) manufacturing field. In the method for forming an alignment measurement mark for measuring the accuracy of pattern overlap between three layers by forming a measurement mark in an in-box shape, two first measurements separated from each other at regular intervals in one direction using a first material film Forming a pattern; Forming two second measurement patterns separated from each other at a predetermined interval in the other direction by using a second material film and forming an outer box together with the first measurement pattern; And forming the photoresist pattern forming the inner box by covering the outer box but providing an open area inside the outer box. The present invention can reduce the measurement time by more than half by simultaneously performing the overlap measurement of the three layers, and can increase the productivity by increasing the accuracy of the measurement, it is possible to prevent the increase of the process time due to repeated measurement .

Description

How to form alignment measurement mark

1 is a layout diagram of a typical DRAM cell.

2A and 2B are plan views of conventional alignment measurement marks.

3a and 3c is a process diagram for forming the outer box of the alignment measurement mark according to the present invention.

4 is a layout diagram of a photomask for forming an inner box of an alignment measurement mark according to the present invention.

5 is a plan view of an alignment measurement mark formed in accordance with the present invention.

6 is a cross-sectional view showing the case where the inner box of the alignment measurement mark does not cover the adjacent outer box.

7 is a view showing the reflected light path of the measurement light source in the alignment measurement mark formed according to the present invention.

* Explanation of symbols for main parts of the drawings

16: first outer box 18: second outer box

20: measuring tube member 25: inner box

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the field of semiconductor and liquid crystal display (LCD) manufacturing, and more particularly, to a method for forming alignment measurement marks for measuring the accuracy of pattern overlap between layers in a lithography process for forming a pattern constituting an element.

In general, the overlapping accuracy between patterns formed on different layers in the micropattern forming process is a very important factor in the lithography process along with the uniformity of the resolution, the depth of focus margin, and the line width. The overlap between patterns required in the semiconductor manufacturing process usually corresponds to 20% to 30% of the size of the fine line width, and as the degree of integration increases, a registration error (instead of measurement in a microscope using visible light) error) Measurement methods using measuring equipment are more widely used because of their accuracy and reproducibility.

A method of measuring a conventional pattern overlapping degree will now be described with reference to FIGS. 1, 2a, and 2b.

First, FIG. 1 shows a layout of a typical DRAM cell, where '1' is an active region, '2' is a wordline, '3' is a bitline contact, '4' is a bitline, and '5' is a Each of the charge storage electrode contacts is shown.

Next, FIG. 2A is a plan view of a conventional measurement mark formed on a scribe line to measure the overlapping accuracy of the word line 2 and the charge storage electrode contact 5 of FIG. ) To form the outer box (6) with the polysilicon film used to form the () and the inner box (7) with the photosensitive film used when forming the charge storage electrode contact (5) to the outer box (6) and the inner box By measuring the distance relationship of (7), the overlapping accuracy of the pattern is measured. Similarly, in order to measure the overlapping accuracy between the bit line 4 and the charge storage electrode contact 5, an outer box 8 is formed of a polysilicon film used when the bit line 4 is formed, and the charge storage electrode contact ( 5) by forming the inner box (7) with the photosensitive film used to form the pattern accuracy is measured. As such, in order to measure the overlapping accuracy between the two patterns, an inner box and an outer box are formed to measure the distance between the two boxes to measure the pattern overlapping accuracy of the contact.

However, in the conventional method of measuring the overlapping accuracy, when measuring the degree of overlap of three interlayer patterns, the measurement mart has three types (first layer to second layer, first layer to third layer, second layer to third layer). Layer) and the superimposition degree should be measured separately for each, resulting in a problem of lowering productivity.

Therefore, the present invention devised to solve the above problems by changing the design of the outer box to perform the pattern overlap accuracy for the three layers at the same time to shorten the measurement time, to form an alignment measurement mark that can improve the reliability of the measurement The purpose is to provide a method.

In order to achieve the above object, the present invention, in the form of a box-in-box in the scribe line region in the alignment measurement mark forming method for measuring the accuracy of pattern overlap between three layers, using a first material film in one direction Forming two first measurement patterns separated from each other at a predetermined interval; The second material film is separated by a predetermined distance in the other direction, and is formed to cover the outer box together with the first measurement pattern, and an open area is provided inside the outer box to form a photoresist pattern forming the inner box. It comprises a step.

Hereinafter, an embodiment according to the present invention will be described in detail with reference to the accompanying drawings.

First, as illustrated in FIG. 3A, two first outer boxes separated from each other at 40 μm intervals in an X direction using a polysilicon film used to form a word line in a die to form a measurement mark. 16).

Next, as shown in FIG. 3B, two second substrates separated from each other at intervals of 40 μm in the Y direction by using a polysilicon film used to form a bit line in the die for measuring the overlap between the word line and the bit line are illustrated. The outer box 18 is formed. As a result, when the first and second outer boxes overlap, an outer box as shown in FIG. 3C is formed.

Subsequently, an inner box (not hatched) is formed in the first and second outer boxes to measure the overlap between the word line and the bit line and the charge storage electrode contact, using a chrome (3) mask pattern as shown in FIG. To form a final measurement mark as shown in FIG. At this time, since the first and second outer boxes are covered by the photoresist pattern, the contrast through the measuring equipment is somewhat reduced, but it is sufficient for the measurer to check the distance (X, X ', Y, Y'). By measuring these distances (X, X ', Y, Y'), the overlap error of the pattern is measured.

The reason for forming the inner box as shown in FIG. 5 is that when the photoresist pattern (inner box) 25 is embossed inside the outer box as in the usual case as shown in FIG. 6, the outer two polysilicon layer patterns 30 (Contrast to the first and second outer boxes 16 and 18 of FIG. 3C), the contrast difference of the light is severely generated and the accuracy of the measurement is not reliable.

FIG. 7 is a cross-sectional view taken along the line A-A 'of FIG. 5 showing the path of the measuring tube incident on the measuring mark according to the present invention. That is, when the measurement light source 20 is incident, it is reflected by the polysilicon film pattern (outer box) 18 and the polysilicon film pattern (outer box) 16 (not shown), and the reflected non-reflected photoresist pattern (22) is reflected back (23) and only a part of the light (21) reaches the meter. Therefore, the difference in contrast by the two polysilicon film patterns 16 and 18 can be significantly reduced.

The present invention made as described above can perform the measurement of the overlap between the three layers at the same time can shorten the measurement time by more than half, and the accuracy of the measurement can be trusted to improve the productivity, and to prevent the increase of the process time due to repeated measurement It has an effect.

Claims (2)

In the method of forming an alignment measurement mark formed in a box-in-box shape in a scribe line region to measure pattern overlap accuracy between three layers, two materials separated from each other at regular intervals in one direction by using a first material film 1 forming a measurement pattern; Forming two second measurement patterns separated from each other by a predetermined distance in the other direction by using a second material film and forming an outer box together with the first measurement pattern; And forming the photoresist pattern forming the inner box by covering the outer box and providing an open area inside the outer box. The method of claim 1, wherein the first measurement pattern and the second measurement pattern are formed in a direction substantially perpendicular to each other.