KR20040056950A - Charging prevention pattern for measuring pattern CD of the photo mask - Google Patents

Abstract

PURPOSE: An electron accumulation preventing pattern in measuring the CD (critical dimension) of photomask is provided to obtain the pattern CD data of photomask measured by SEM precisely. CONSTITUTION: The electron accumulation preventing pattern comprises a chip pattern(120) formed in the core on a light transmitting substrate(100); a conductive light screening film(110) formed in the surrounding of the core on the light transmitting substrate; and at least one conductive bridge(130) which connects the chip pattern and the conductive light screening film on the light transmitting substrate and emits the electron(140) accumulated in the chip pattern outside. Preferably the chip pattern, the conductive light screening film and/or the conductive bridge are made of metal or metal composite film. Preferably the CD of the conductive bridge is wider than the CD resolution of an exposure device by 4-5 times.

Description

Charging prevention pattern for measuring pattern CD of the photo mask}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photomask of a semiconductor device, and more particularly, to an electron accumulation prevention pattern during linewidth measurement of a photomask.

BACKGROUND OF THE INVENTION A manufacturing process of a semiconductor device performs a plurality of photolithography processes to form elements on a surface of a semiconductor substrate. Furthermore, in order to form a highly integrated circuit, a photomask having a fine pattern is required and there should be no defect in this pattern. The size of the critical dimension (hereinafter referred to as 'CD') required by the high integration of semiconductor devices has already reached the limit of the resolution of exposure equipment. In this situation, the CD uniformity of the pattern on the photomask for patterning a certain material layer is very important.

In the manufacture of photomasks, defect inspection of masks and measurement of pattern CDs are generally performed in separate processes using different equipment. In order to measure pattern CDs of photomasks, a scanning electron microscope (Scanning) is used. Electron Microscope (hereinafter referred to as SEM), edge diffraction detection using optical systems or lasers are mainly used.

1 is a plan view illustrating a photomask according to the prior art, wherein the photomask includes a chip pattern 30 formed on a core on an upper portion of the light transmissive substrate 10, and a conductive light shielding film formed around the core on the light transmissive substrate 10. 20). Here, the light transmissive substrate 10 is formed of glass or quartz. The conductive light shielding film 20 is formed of a metal such as nickel (Ni), chromium (Cr), and cobalt (Co) to prevent visible or ultraviolet rays from transmitting. The chip pattern 30 is formed with a fine circuit pattern made of a light transmissive substrate 10 and a conductive light shielding film 20.

2 is a view showing the measurement of the line width (CD) of the photomask by a scanning electron microscope (SEM) by the prior art.

As shown in FIG. 2, when the electron beam 40 is emitted from the electron gun 50 of the SEM, the electron beam 40 is incident on the surface of the chip pattern 30 of the photomask. When the electron beam 40 is incident on the chip pattern 30, electrons, secondary electrons, X-rays, and the like reflected from the chip pattern 30 are generated. In the SEM, the secondary electrons are detected and converted into electrical signals to display a pattern image of the chip pattern 30 to measure the CD of the pattern.

However, when the CD of the photomask is measured, electrons 40 irradiated from the SEM flow through the conductive light shielding film 20. The chip pattern is caused by the light transmissive substrate 10 between the chip pattern 30 and the conductive light shielding film 20. Electrons in 30 do not flow out of the photomask and are accumulated on the surface of the chip pattern 30 without being emitted. The electrons accumulated in the chip pattern 30 bend the direction of electrons irradiated from the electron gun of the SEM, thereby reducing the amount of secondary electrons. If the secondary electrons are reduced, the pattern image measured in the SEM may become unclear or jittery, resulting in difficulty in measuring the pattern CD of the photomask or obtaining accurate measurement values.

The purpose of the present invention is to solve the above problems of the prior art by forming a conductive bridge having a fine line width on the light-transmitting substrate around the chip pattern by conducting electrons accumulated on the chip pattern surface during CD measurement of the photomask by SEM The amount of the secondary electrons which are extracted from the SEM through the bridge is constant, thereby providing an electron accumulation prevention pattern in the measurement of the line width of the photomask, which can improve the accuracy of CD measurement of the photomask pattern.

1 is a plan view showing a photomask according to the prior art,

2 is a view showing measuring the line width of the photomask with a scanning electron microscope according to the prior art,

3 is a plan view showing a photomask according to the present invention.

* Description of the symbols for the main parts of the drawings *

100: light transmissive substrate

110: conductive shielding film

120: chip pattern

130: challenge bridge

140: electronic

In order to achieve the above object, the present invention provides a photomask comprising a chip pattern formed on a core of an upper portion of a light transmissive substrate, a conductive light shielding layer formed around a core of an upper portion of the light transmissive substrate, and a chip pattern and a conductive light shielding layer formed on an upper portion of the light transmissive substrate. And a conductive bridge for emitting electrons accumulated in the chip pattern to the outside.

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

3 is a plan view showing a photomask according to the present invention. Referring to FIG. 3, the photomask according to the present invention may include a chip pattern 120 formed on a core on the light transmissive substrate 100, a conductive light shielding film 110 formed around the core on the light transmissive substrate 100, and light. A conductive bridge 130 is connected between the chip pattern 120 and the conductive light shielding film 110 on the transparent substrate 100 and emits electrons accumulated in the chip pattern 120 to the outside.

Here, the light transmissive substrate 100 is formed of glass or quartz. The conductive light shielding film 110 is formed of a metal such as nickel (Ni), chromium (Cr), cobalt (Co), or a metal composite film such as molybdenum silicide (MoSiN) so that visible light or ultraviolet light cannot be transmitted. The chip pattern 120 has a fine circuit pattern formed of the light transmissive substrate 100 and the conductive light shielding film 110.

The conductive bridge 130 newly added to the photomask by the present invention is a metal such as nickel (Ni), chromium (Cr), and cobalt (Co), such as the conductive light shielding film 110, or molybdenum silicide (MoSiN). It consists of metal composite films, such as these. In addition, at least one conductive bridge 130 is formed on the photomask, and the number thereof is not a problem. If only one conductive bridge 130 can serve as a path for electrons accumulated in the photomask.

Meanwhile, when the conductive light shielding film 110 and the conductive bridge 130 of the present invention are formed of a metal, a general photomask may be manufactured, and when the conductive light shielding film 110 and the conductive bridge 130 are formed of a metal composite film of molybdenum silicide (MoSiN), a phase inversion photomask may be manufactured. .

When the CD is measured using the photomask according to the present invention configured as described above, electrons 140 irradiated from the SEM accumulate on the surface of the chip pattern 120, wherein the chip pattern 120 and the conductive light shielding film 110 are used. The electrons 140 accumulated by the conductive bridges 130 connecting them flow out from the chip pattern 120 to the outside. The electrons do not accumulate inside the chip and escape to the outside. Accordingly, the electrons irradiated from the electron gun of the SEM are irradiated onto the surface without being affected by the electrons accumulated in the chip pattern 120, so that the amount of the secondary electrons is kept constant. In the SEM, the chip pattern 120 is not isolated. A clear pattern image of a degree obtainable can be obtained, and the pattern CD measurement of the photomask is improved.

In the conductive bridge 130 added to the photomask of the present invention, the CD varies according to the design rule, and the criterion is related to the resolution of an exposure field such as a stepper or a scanner used during wafer exposure. Since a normal photomask has four or five times the size of a wafer CD, the CD of the conductive bridge 130 can realize four times or five times the size of a CD that is not realized by the resolution of wafer exposure equipment. Implementing on a photomask is not a problem. For example, if the minimum implementation resolution of the wafer exposure equipment is 0.1 µm or more, the CD of the conductive bridge 130 implemented in the photomask is 0.4 µm to less than 0.5 µm.

As described above, the photomask fabrication method of the present invention is not different from the conventional mask fabrication method, and only the change data for forming the conductive bridge may be used for the writing data used in the exposure process.

As described above, the present invention can accurately obtain the pattern CD data of the photomask in the SEM by adding a conductive bridge that emits electrons accumulated in the photomask when the CD of the photomask is measured by the SEM. The accuracy of the measurement can be improved.

On the other hand, the present invention is not limited to the above-described embodiment, various modifications are possible by those skilled in the art within the spirit and scope of the present invention described in the claims to be described later.

Claims (6)

In the photomask, A chip pattern formed on the core on the light transmissive substrate; A conductive light shielding film formed around a core on the light transmissive substrate; And And a conductive bridge connecting the chip pattern and the conductive light shielding film on the light transmissive substrate and emitting electrons accumulated in the chip pattern to the outside. The pattern of claim 1, wherein the chip pattern is formed of a metal or a metal composite film pattern. The pattern of claim 1, wherein the conductive light shielding film is formed of a metal or a metal composite film. The pattern of claim 1, wherein the conductive bridge is made of a metal or a metal composite film. The pattern of claim 1, wherein the conductive bridge has at least one conductive bridge. The pattern of claim 1, wherein the line width of the conductive bridge has a line width of 4 to 5 times the line width resolution of the exposure apparatus.