KR20100010696A - Photomask having alignment pattern for inspecting photomask and method for fabricating the same - Google Patents

Abstract

PURPOSE: A photomask having an alignment pattern for an inspecting photomask and a method for fabricating the same are provided to the defective due to a foreign substance by forming an arranging pattern on the rear side of the mask substrate. CONSTITUTION: A circuit pattern is formed on a light-transmissive substrate. A mask alignment pattern(210) is formed on the rear side of the light-transmissive substrate. The photomask alignment pattern is formed of a carbon film(220). The photomask alignment pattern is arranged to have the same coordinate system of mask alignment pattern. A resist film is spread on the rear side of the photomask(200) in which the carbon film is formed and the resist film(230) is formed.

Description

Photomask having alignment pattern for inspecting photomask and manufacturing method therefor {Photomask having alignment pattern for inspecting photomask and method for fabricating the same}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photomask and a method of manufacturing the same, and to a photomask having a photomask inspection alignment pattern capable of grasping a precise position of a growth foreign material generated on the rear surface of a photomask and a method of manufacturing the same.

In recent years, as the size of a semiconductor element is reduced in size and capacity, the size of a pattern to be formed is also decreasing. Accordingly, light having a short wavelength is used as a light source to realize a desired level of resolution. An ArF excimer laser having a wavelength of 193 nm is mainly used. However, in the case of the ArF excimer laser, due to the high energy, salts which are reaction by-products remain on the surface of the photomask by reacting with organic or inorganic substances present on or around the surface of the photomask. This phenomenon is known to occur when the energy accumulated in the photomask increases during exposure to form a pattern on the wafer using an ArF excimer laser continuously using a normally manufactured photomask. In particular, the foreign matter that occurs on the back side of the photomask may be due to a substance in the surrounding environment. In severe cases, it may be visually observed.

These salts reduce the transmittance of the light source passing through the photomask to change the appropriate exposure energy to form the desired pattern on the wafer, thereby threatening the stability of the process, as well as causing local differences in transmittance to form on the wafer. The uniformity of the pattern is reduced, and ultimately, it is a great factor that lowers the manufacturing yield of the semiconductor device.

Therefore, to solve this problem, it is necessary to accurately analyze the cause of the occurrence of these salts, and in order to do this, it is necessary to first confirm the exact location of the generated by-products. However, in the related art, since there was no method for determining the exact location of the growth foreign material generated on the back side of the photomask, accurate analysis of the growth foreign material located in the desired area could not be performed.

The technical problem to be achieved by the present invention is to determine the alignment pattern for the photomask inspection that can improve the various problems caused by the growth foreign material by grasping the exact position of the growth foreign material generated on the back of the photomask using the ArF excimer laser as a light source. It is to provide a photomask to be provided.

Another object of the present invention is to provide a method of manufacturing a photomask having an alignment pattern for inspecting a photomask.

In order to achieve the above technical problem, the photomask according to the present invention is characterized in that it comprises a light transmissive substrate, a circuit pattern formed on the upper surface of the light transmissive substrate, and a photomask inspection alignment pattern formed on the rear surface of the translucent substrate.

The alignment pattern for inspecting the photomask may be formed of a carbon film.

The photomask inspection alignment pattern may be disposed to have the same coordinate system as the mask alignment pattern included in the circuit pattern.

The photomask inspection alignment pattern may have a thickness such that a transmittance of a light source having a wavelength of 190 nm to 250 nm is 50 to 80%.

In accordance with another aspect of the present invention, there is provided a method of manufacturing a photomask, wherein a material film for forming an alignment pattern is formed on a region of a photomask inspection alignment pattern on a rear surface of a translucent substrate on which a circuit pattern is formed. Forming a resist, applying a resist to the back surface of the substrate on which the material film is formed, exposing the resist by irradiating a light source from an upper surface of the substrate, and developing a resist pattern to expose a portion of the material film. And forming an alignment pattern for photomask inspection by removing the resist pattern and etching the material film of the exposed region.

The forming of the material film may include depositing a carbon film on a region where an alignment pattern is to be formed using a focused ion beam (FIB).

The etching of the material layer may be performed by using a laser repair apparatus.

The photomask inspection alignment pattern may be formed to have the same coordinate system as the pattern for mask alignment included in the circuit pattern.

The material film for forming the alignment pattern may be formed to a thickness such that the transmittance of the light source having a wavelength of 190 nm to 250 nm is 50 to 80%.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, embodiments of the present invention may be modified in many different forms, and the scope of the present invention should not be construed as being limited by the embodiments described below.

1 is a view showing an example of an alignment pattern for a photomask inspection according to the present invention.

Referring to FIG. 1, an alignment pattern 110 is provided on a rear surface of a photomask to be used in an inspection apparatus. The alignment pattern 110 for inspecting the photomask may be formed of a carbon film. The alignment pattern 110 for inspecting the photomask may be disposed to have the same coordinate system as the mask alignment pattern included in the circuit pattern disposed on the front surface of the photomask. The alignment pattern 110 may have a thickness such that a transmittance of a light source having a wavelength of 190 nm to 250 nm is 50 to 80%.

After the mask alignment process is performed in the photomask inspection apparatus, the position information of the growth foreign material may be accurately determined based on the alignment pattern 110. At this time, in order to match the coordinate system of the back surface of the photomask and the pattern surface, the relative position values of the two alignment patterns must be known. In the present invention, the alignment pattern of the pattern surface and the back surface of the photomask is formed at the same position, thereby more accurately matching the coordinate system. Can be achieved.

2 to 5 are cross-sectional views illustrating a method of forming an alignment pattern for inspecting a photomask according to an embodiment of the present invention.

Referring to FIG. 2, a carbon film 220 is formed in a region where an alignment pattern is to be formed on the rear surface of the photomask 200 on which the predetermined pattern 210 is formed. On the photomask 200, a light shielding film pattern 210 for implementing a predetermined circuit pattern for manufacturing a semiconductor device is formed. The light blocking film pattern 210 includes a pattern 215 for mask alignment. The carbon film 220 may be formed by depositing using a focused ion beam (FIB). When forming the carbon film 220, it is preferable to adjust the thickness so that the transmittance of the light source of 190 nm to 250 nm wavelength is about 50 to 80%.

Referring to FIG. 3, a resist is entirely coated on the back surface of the photomask 200 on which the carbon film 220 is formed to form a resist film 230. The resist film 230 is exposed using an exposure apparatus. As shown in the drawing, only a region where the carbon film 220 is formed is exposed by irradiating a light source from the upper surface of the photomask on which the pattern 210 is formed.

Referring to FIG. 4, the exposed resist film is developed to form a resist pattern 230a exposing a region where an alignment pattern is to be formed. The carbon film exposed by the resist pattern 230a is etched to form an alignment pattern 220a for locating the growth foreign material generated on the back surface of the photomask. The process of etching the carbon film can be performed using a laser repair apparatus. Since the mask is masked by the resist pattern 230a in an area other than the alignment pattern, the mask substrate 200 or the light blocking film pattern 210 formed on the mask substrate is protected without being etched.

Referring to FIG. 5, when the resist pattern used as a mask is removed, a circuit pattern 210 is formed on an upper surface, and an alignment pattern 220a is formed on the rear surface of the substrate to determine a position of a growth foreign material. The mask is complete. The alignment pattern 220a has the same coordinate system as the alignment pattern for the circuit pattern formed on the upper surface of the mask substrate 200.

As described above, according to the method for forming an alignment pattern for photomask inspection according to the present invention, ArF is formed by forming an alignment pattern having the same coordinate system on the rear surface of the mask substrate as the alignment pattern for the circuit pattern formed on the upper surface of the mask substrate. Accurate positions of growthable foreign matters generated during the exposure process using an excimer laser, foreign matters generated during photomask manufacture, and the like can be identified. Therefore, when the analysis using the device, such as physical or chemical analysis can be accurately analyzed the defect of the desired position, it is possible to fundamentally approach the cause of the growth of foreign matter and can easily take action. In addition, even in the case of foreign matter generated in the manufacturing process, it is easy to grasp the cause. In addition, since it is possible to quantify the influence of the wafer pattern process due to the defect of the back surface of the growth foreign material or the mask, more flexible response can be made.

The present invention is not limited to the above embodiments, and various modifications can be made by those skilled in the art within the technical spirit of the present invention.

1 is a view showing an example of an alignment pattern for inspecting a photomask formed on the rear surface of a photomask according to the method of the present invention.

2 to 5 are cross-sectional views illustrating a method of forming an alignment pattern for inspecting a photomask according to an embodiment of the present invention.

Claims (9)

Translucent substrate; A circuit pattern formed on an upper surface of the light transmissive substrate; And And a photomask inspection alignment pattern formed on the back surface of the light transmissive substrate. The method of claim 1, The photomask inspection alignment pattern is a photomask, characterized in that made of a carbon film (carbon). The method of claim 1, The photomask inspection alignment pattern is arranged to have the same coordinate system as the mask alignment pattern included in the circuit pattern. The method of claim 1, The photomask inspection alignment pattern has a thickness such that the transmittance of a light source having a wavelength of 190 nm to 250 nm is 50 to 80%. Forming a material film for forming an alignment pattern on a region on which the alignment pattern for photomask inspection is to be formed on the back surface of the light transmissive substrate having a circuit pattern formed thereon; Applying a resist to the back surface of the substrate on which the material film is formed; Exposing the resist by irradiating a light source from an upper surface of the substrate; Developing the exposed resist to form a resist pattern exposing a portion of the material film; Etching the material film in the exposed region; And And removing the resist pattern to form an alignment pattern for inspecting the photomask. The method of claim 5, Forming the material film, A method of manufacturing a photomask, comprising depositing a carbon film on a region where an alignment pattern is to be formed using a focused ion beam (FIB). The method of claim 5, The etching of the material film may be performed using a laser repair apparatus. The method of claim 5, The photomask inspection alignment pattern may be formed to have the same coordinate system as the pattern for mask alignment included in the circuit pattern. The method of claim 5, The material film is a photomask, characterized in that formed in a thickness such that the transmittance of the light source of 190nm to 250nm wavelength is 50 to 80%.

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