KR100207445B1 - Photomask fabriccating method - Google Patents

Abstract

A method of forming a fine pattern using electron beam irradiation has been described.

This includes the steps of applying a photoresist film on a substrate, a step of exposing and developing the photoresist film to form a photoresist pattern, and a step of irradiating an electron beam to the resultant formed photoresist pattern.

Therefore, it is possible to form a finer pattern, there is an advantage that can proceed the process in anticipation of the final line width.

Description

Photomask Manufacturing Method

1A to 1C are cross-sectional views illustrating a method of manufacturing a photomask using a method for forming a micropattern by electron beam irradiation of the present invention.

FIG. 2 is a SISCAN photograph showing that the line width is reduced by irradiating an electron beam after the formation process of the electron beam resist.

FIG. 3 is a scanning electron microscope (SEM) image of the same photomask of FIG. 2.

4 is a scanning electron microscope (SEM) photograph after the photomask is processed to the final cleaning process.

* Explanation of symbols for main parts of the drawings

10 substrate 12 light shielding film

14 non-reflective film 16 electron beam resist

The present invention relates to a method of manufacturing a photomask, and in particular, in the photolithography process, after the development process, a fine pattern forming method capable of obtaining an accurate line width and uniform edge roughness by irradiating an electron beam to the entire surface. It is about.

In the manufacture of semiconductor integrated circuits, the amount of impurities injected into the microscopic areas of the silicon substrate must be precisely controlled and at the same time these regions must be interconnected. It is well known that patterns defining these areas are formed by photolithography techniques.

According to the photolithography technique, a photosensitive film whose solubility is changed by irradiation of light such as ultraviolet rays, electron beams, or X-rays is formed on a film on which a pattern such as an insulating film or a conductive film on a semiconductor substrate is to be formed. After exposing the site to light, a photosensitive film pattern is formed by removing a portion having high solubility with respect to the developer, and an exposed part of the film to be formed is removed by etching to form various patterns such as wiring and electrodes.

In photolithography, the development process is the one that most affects the line width accuracy and edge roughness of the pattern except for the exposure process. This is because if the developing process goes wrong, only a small amount of compensation is possible in the subsequent process (usually 0.5 Degree).

Since the development process is based on the difference in the solubility of the photoresist film in the developer of the irradiated and unirradiated portions, the difference in solubility increases as the process progresses longer, so that the development process is generally slightly exceeded. It is advantageous to carry out. However, at least 0.4 in subsequent descum and ethching processes Since the above line width is reduced, at least 0.4 to the final line width even if the development process is exceeded. Since it is necessary to have the above line width value, the developing step cannot be lengthened.

In most cases, the development process is carried out with a slight deficiency, the line width value is measured, and then further development process is performed. However, in this case, the additional developing process has no objective data, that is, no objective data on the change of the line width with the time of the further developing process, and the change of the line width with respect to the additional developing time appears irregularly without reproducibility. It is also impossible to set.

An object of the present invention is to provide a fine pattern forming method that can obtain an accurate line width and uniform edge roughness even under submicron.

A photomask manufacturing method having a micropattern of the present invention for achieving the above object comprises the steps of applying a light shielding film on a transparent substrate, applying an electron beam resist on the light shielding film, and exposing and developing the electron beam resist electron beam resist Forming a pattern, and adjusting a line width of the electron beam resist pattern by irradiating an electron beam to the entire surface of the resultant in which the electron beam resist pattern is formed. At this time, the photomask is preferably a transmissive photomask.

According to the present invention, the pattern can be formed more finely, and the process can be performed in anticipation of the final line width.

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

The fine pattern forming method according to the present invention is characterized by improving the line width and the edge roughness by inserting the electron beam irradiation step in the middle of the (1) development (2) baking (3) disc (4) etching process. According to a preferred embodiment of the present invention, it is most preferable to insert the electron beam irradiation step between the developing step and the baking step.

EXAMPLE

As an embodiment using the method for forming a fine pattern of the present invention, an example applied to the manufacture of a photomask having a pattern to be transferred to a wafer will be described with reference to FIGS. 1A to 1C.

The conventional manufacturing process of a general photomask includes (1) forming a light shielding film on a substrate, (2) forming a non-reflective film, (3) applying a photosensitive film, (4) exposing a pattern on a photosensitive film, (5) developing (development), and (⑥) baking. ) Process, ⑦ descum process, ⑧ etching process, ⑨ strip and ⑩ cleaning process.

In the photomask fabrication process according to an embodiment of the present invention, the line width and edge roughness of the pattern formed on the photomask by irradiating an electron beam in the middle of the development- bake-discom-etch process in the conventional photomask fabrication process. I can regulate it.

1A is a cross-sectional view of the step of forming the light shielding film 12 and the anti-reflective film 14 on the substrate.

Specifically, chromium (Cr), which is a light shielding material, is applied to a substrate 10, for example, a transparent glass substrate or a quartz substrate, by the sputtering method to form a light shielding film 12, and then, on the light shielding film, A non-reflective film 14 is formed by depositing a chromium oxide (CrO) series, which is a reflective material.

FIG. 1B is a cross-sectional view of forming the electron beam resist pattern 16 and electron beam irradiation step.

Specifically, the electron beam resist pattern 16 is formed by applying an electron beam resist on the antireflective film, exposing the electron beam resist to a light source such as an electron beam or ultraviolet rays, and then developing the electron beam resist. Subsequently, the electron beam is irradiated on the entire surface of the substrate on which the electron beam resist pattern is formed.

FIG. 1C is a cross-sectional view of a step of completing a photomask. After baking and descoming the result of the electron beam irradiation, the antireflective film and the light shielding film are etched using the electron beam resist pattern as a mask, and then the cleaning process is performed. The photomask is completed.

Since the electron beam irradiation method can obtain the final line width by adjusting the line width of the electron beam resist pattern, it can be applied to the manufacture of both a transmission type photomask and a phase inversion mask.

According to the embodiment of the present invention, the line width of the pattern can be reduced and the edge roughness can be improved by the electron beam irradiation process. Experimental results show that one side of the line width is approximately 0.3 It can be reduced to about (0.6 on both sides) ).

The reduction of the line width and the improvement of the edge roughness may be achieved by using a solvent or isopropyl alcohol (IPA) component contained in a developer or a post-development cleaning solution in a free volume of the electron beam resist pattern. This is achieved by removing the electron beam resist pattern while the components are activated by irradiation of the electron beam.

FIG. 2 is an optical microscope and a SIScan (SISCAN: laser and ultraviolet light measurement optical microscope) photograph showing the reduction of the line width by irradiating the electron beam after the electron beam resist developing process.

In FIG. 2, the black part is the electron beam resist, and the white line in the center is the upper surface of the electron beam resist, and the light is reflected and appears white. The portion where the line width of the electron beam resist pattern is narrow is the portion where the electron beam is irradiated. Left and right 0.3 About 0.6 This has been reduced.

FIG. 3 is a photograph of the same photomask of FIG. 2 as a scanning electron microscopy (SEM).

FIG. 4 is a SEM photograph of the photomask after the final cleaning process, in which the portion irradiated with the electron beam is shown as the line width is reduced as it is, and it can be seen that the edge roughness is improved than the portion not irradiated with the electron mask. The line width at this time does not deviate significantly from the line width measured at the time of electron beam irradiation (specifically 0.05 Degree).

As described above, according to the method for forming a micropattern according to the present invention, the development process is insufficient and irradiated with an electron beam again without further processing, thereby compensating for the insufficient development process and forming a finer pattern. In addition, there is an advantage that the process can proceed in anticipation of the final line width.

The present invention is not limited to the above embodiments, and it is apparent that many modifications are possible by those skilled in the art within the technical spirit of the present invention.

Claims (2)

Applying a light shielding film on the transparent substrate; Applying an electron beam resist on the light shielding film; Exposing and developing the electron beam resist to form an electron beam resist pattern; And irradiating an electron beam on the entire surface of the resultant product on which the electron beam resist pattern is formed to adjust a line width of the electron beam resist pattern. The method of claim 1, wherein the adjusting the line width of the electron beam resist pattern by irradiating an electron beam on the entire surface of the resultant on which the electron beam resist pattern is formed is performed before developing and baking the electron beam resist. Manufacturing method.