KR20100000621A

KR20100000621A - Optical alignment measurement apparatus

Info

Publication number: KR20100000621A
Application number: KR1020080060186A
Authority: KR
Inventors: 박신애
Original assignee: 주식회사 하이닉스반도체
Priority date: 2008-06-25
Filing date: 2008-06-25
Publication date: 2010-01-06

Abstract

The present invention comprises an optical alignment measuring apparatus including a color filter for selectively classifying light sources and an illumination system for adjusting the resolution of the light source passing through the color filter.

Description

Optical alignment measurement apparatus

The present invention relates to an optical alignment measuring device, and more particularly, to an optical alignment measuring device for improving the reliability of alignment by applying an illumination system.

The manufacturing process of a semiconductor element includes the process of aligning a lower structure and an upper structure. In this case, as the alignment margin between the substructure and the superstructure is matched, reliability of the semiconductor device may be improved.

There are several ways to set the alignment margin, and the method of measuring alignment margin using an overlay pattern which is generally used is described as an example.

1A and 1B are diagrams for explaining a principle of alignment measurement using an overlay pattern.

Referring to FIG. 1A, an overlay pattern is a pattern formed for measuring alignment margin in a region (eg, a scribe region) that is not substantially used in a semiconductor device. For example, the Oberoi pattern may be formed of the outbox 12, the reflective layer 14, and the inbox 15 formed in a predetermined pattern on the semiconductor substrate 10. When the light source is irradiated to the overlay pattern, the difference between the intensity of the light source reflected by the light source T reflected through the region where the opening A is formed and the light source M reflected through the region where the pattern A is formed is measured. Measurement can be aligned. That is, the intensity difference of the light source can be measured according to the medium.

On the other hand, as the degree of integration of semiconductor devices increases, the size of the alignment measurement pattern decreases, making it increasingly difficult to analyze the alignment measurement value. For example, if the error of the difference in intensity of the light source is not accurately measured, alignment error may occur by that amount, and thus the reliability of the semiconductor device may be degraded.

An object of the present invention is to further reduce the error range of the measurement data by additionally equipped with an illumination system in the alignment measurement device, thereby improving the reliability of the semiconductor manufacturing process.

An optical alignment measuring device according to the present invention includes a color filter for selectively classifying light sources. It consists of an optical alignment measuring device including an illumination system for adjusting the resolution of the light source passing through the color filter.

The illumination system includes a polarizing plate for polarizing the light source passing through the color filter into an ellipse having a constant ellipticity and polarization angle. An aperture for controlling the light shielding efficiency of the light source passing through the polarizing plate. And a condenser lens for focusing the light source passing through the aperture on the wafer.

The aperture is implemented in an annular, quadrupole or crosspole alignment.

The present invention can further reduce the error range of alignment measurement data by additionally attaching an illumination system to the alignment measurement device, thereby improving the reliability of the semiconductor manufacturing process.

Hereinafter, with reference to the accompanying drawings will be described a preferred embodiment of the present invention. However, the present invention is not limited to the embodiments disclosed below, but can be implemented in various forms, and only the present embodiments are intended to complete the disclosure of the present invention and to those skilled in the art. It is provided for complete information.

2 is a view for explaining an alignment measuring device of a semiconductor device according to the present invention.

Referring to FIG. 2, the alignment measuring apparatus includes a color filter 200 for selectively classifying light sources and an illumination system 210 for finely adjusting the intensity of the light sources. Specifically, it is as follows.

The light source is irradiated to the color filter 200. The light source classified from the color filter 200 is irradiated to the illumination system 210. The illumination system 210 includes a polarizing plate 211, an aperture 212, and a condenser lens 213. In detail, the light source passing through the color filter 200 passes through the polarizing plate 211, the aperture 212, and the condenser lens 213 and enters the wafer 220. The polarizing plate 211 serves to polarize the light source into an ellipse having a constant ellipticity and polarization angle by controlling X polarization and Y polarization. The light source passing through the polarizing plate 211 enters the aperture 212. The aperture 212 may adjust light blocking efficiency of the light source, which will be described in detail with reference to FIG. 3. FIG. 3 is a plan view for describing the type of aperture of FIG. 2.

Referring to FIG. 3, the aperture 212 may be implemented as a combination of conventional, annular, quadrupole, or crosspole. Conventional apertures have a single sigma value and are therefore less accurate than the other apertures shown. Accordingly, it is preferable to use an annular, quadrupole or crosspole aperture for the aperture. Each of the annular, quadrupole, or crosspole apertures can adjust the outside sigma (O) and inside sigma (I) values to improve -1, 0, and primary light efficiency. It is easy to For example, when the efficiency of the primary light is higher than 40%, resolution is possible. Specifically, the following description will be given with reference to FIGS. 4A to 4C.

4A to 4C are diagrams for explaining alignment measurement values due to light quantity differences.

4A shows a preferred example than FIG. 4B or 4C. 4A is a graph measured when the amount of light of the trench light source T passing through the trench and the mesa light source M passing through the region other than the trench is the same. For reference, FIG. 4B is a measured value when the trench light amount T is small in the mesa light amount M, and FIG. 4C is a measured value when the trench light amount T is larger than the mesa light amount M. In FIG. As can be seen in the drawing, since the trench light amount T and the mesa light amount M are measured to be similar to the shape of the overlay pattern, the trench light amount T and the mesa light amount M are adjusted by adjusting the illumination system 210. It is desirable to be equal. In addition, the light source passing through the illumination system is derived as -1st order, 0th order and + 1st order (order) light by diffraction phenomenon. At this time, -primary light is removed by pupill filtering, and zero-order light and + 1-primary light are formed on the wafer 220. Next, the condenser lens 213 serves to condense the light source onto the wafer 220. do.

When the illumination system 210 including the polarizing plate 211, the aperture 212, and the condenser lens 213 is used, the contrast of the measured value can be improved by increasing the ratio of +1 order light to 0 order light.

5 is a view for explaining an alignment measurement value according to the present invention.

Referring to FIG. 5F, it can be seen that the alignment measurement according to the present invention can more accurately implement a profile of an alignment pattern, such as an overlay pattern, than in the prior art.

6A is a plan view of a pattern according to a conventional exposure method, and FIG. 6B is a plan view of a pattern according to an exposure method of the present invention.

6A and 6B, even when the exposure and development processes are performed using the above-described illumination system 210 of FIG. 2, a cleaner pattern may be formed than before. For example, a pattern in the X-axis direction applies a dipole Y and an X-polarizing plate, a pattern in the Y-axis direction applies a dipole X and a Y-polarizing plate, and a pattern having both X and Y-axis directions simultaneously cross By applying crosspole or annular apertures, a pattern with high resolution can be obtained. This is because the ratio of the primary light to the zeroth light in the exposure step is high, resulting in high contrast. T not described is a trench, and M is a photoresist pattern.

When applied to overlay equipment such as exposure using an illumination system forms a cleaner pattern (overlay vernier is a pattern having X and Y directions simultaneously, an illumination system such as crosspole or annular) is used. Accurate measurements can be obtained.

Although the technical spirit of the present invention described above has been described in detail in a preferred embodiment, it should be noted that the above-described embodiment is for the purpose of description and not of limitation. In addition, the present invention will be understood by those skilled in the art that various embodiments are possible within the scope of the technical idea of the present invention.

2 is a view for explaining an optical alignment measuring apparatus according to the present invention.

FIG. 3 is a plan view for describing the type of aperture of FIG. 2.

6A is a plan view of a pattern according to a conventional exposure method.

6B is a plan view of a pattern according to the exposure method of the present invention.

10 semiconductor substrate 12 outbox

14: reflective layer 15: inbox

A: opening 200: color filter

210: illumination system 211: polarizing plate

212 aperture 213 condenser lens

220: wafer

Claims

A color filter for selectively classifying light sources; And

And an illumination system for adjusting the resolution of the light source passing through the color filter.

The method of claim 1, wherein the illumination system,

A polarizing plate for polarizing the light source passing through the color filter into an ellipse having a constant ellipticity and polarization angle;

An aperture controlling light blocking efficiency of the light source passing through the polarizing plate;

And a condenser lens for focusing the light source passing through the aperture on the wafer.

The method of claim 2,

And the aperture is implemented as an annular, quadrupole or crosspole alignment.