KR100278645B1 - Halftone phase inversion mask and manufacturing method thereof - Google Patents

Abstract

The present invention relates to a halftone phase reversal mask having a pattern formation region in which a constant pattern is formed and a light transmittance of the region thereof, and a manufacturing method thereof.

A pattern forming region provided in the center portion on the transparent substrate is formed, and a blind region in which light is not transmitted is formed on the peripheral substrate of the pattern forming region. The blind area has a double stacked structure of a shifter and a light shielding pattern on a substrate or a grating pattern of a repetitive line-space or checkerboard. Transmission of light at the time of exposure in the blind region is suppressed, so that a precise pattern can be obtained on the substrate.

Description

Halftone phase inversion mask and manufacturing method thereof

1 is a cross-sectional view showing an example of a conventional halftone phase inversion mask.

2 is a plan view showing an example of a conventional halftone phase inversion mask.

3 and 4 are cross-sectional views showing halftone phase inversion masks according to the present invention.

5A to 5D are cross-sectional views illustrating a method of manufacturing the halftone phase inversion mask shown in FIG.

6A through 6C are cross-sectional views illustrating a method of manufacturing the halftone phase inversion mask shown in FIG.

The present invention relates to a halftone phase shift mask and a method of manufacturing the same. More specifically, the present invention relates to a halftone phase inversion mask having a different light transmittance in a pattern forming region in which a constant pattern is formed and other portions thereof, and a method of manufacturing the same.

In general, it is widely known that various patterns of semiconductor devices are formed by photolithography techniques. According to the photolithography technique, a photosensitive film whose solubility is changed by irradiation with light such as X-rays or ultraviolet rays is formed on a film, such as an insulating film or a conductive film of a semiconductor substrate, to form a pattern, and a predetermined portion of the photosensitive film is formed. After exposing to light, the photoresist pattern is formed by removing the part having high solubility with respect to the developer, and the exposed part of the film to be formed is removed by etching to form various patterns such as wiring and electrodes.

In recent years, technology for forming finer patterns has been developed in accordance with the trend of higher integration and higher density of semiconductor devices. For example, many studies have been conducted on exposure beams using electron beams, ion beams, or X-rays, modified illumination methods using diffracted light of a light source, new resist materials, resist processing methods, and the like.

Recently, the Phase Shift Method, which increases the resolution using a pattern of a mask, has been proposed and attracts great attention (Reference: IBM 1986, IEEE Trans, Elect. Devices. Vol. ED-29, 1982). CP 1828: 1988, Fall Applied Physics Meeting 4a-K-7, 8 (p. 497). The phase inversion method is a method of exposing a pattern using a mask including a phase shifter (hereinafter referred to as a "phase inversion mask").

The phase inversion mask exposes a pattern of a desired size using interference or partial interference of light, thereby increasing resolution or depth of focus.

That is, when light passes through the mask substrate or through the shifter film, the wavelength is shortened by dividing the wavelength in vacuum by the refractive index. Therefore, the light of the same phase is different depending on the presence or absence of the shifter, and if the optical path difference is θ, θ = 2π + (n-1) / λ (where n is the refractive index of the shifter, t is the thickness of the shifter, λ is the wavelength used), and when θ is π, the light rays passing through the shifter have an inverse phase. Therefore, since the light passing through the light transmitting portion and the light passing through the shifter are in phase out from each other, when the shifter is positioned at the edge of the mask pattern, the intensity of light becomes zero at the boundary portion of the pattern, and the contrast increases.

Unlike other conventional fine pattern formation methods, such a phase reversal mask can improve the resolution of the mask by about 30% by reversely diffracting light by only changing the mask manufacturing method without adding new equipment. It is considered as a powerful mass production technology.

As an example of a phase inversion mask using the above principle, an alternating phase shifter in which electric field waves are relatively opposite directions between two lines by alternately arranging shifters when line spaces are densely repeated. A mask, an auxiliary shifter-added mask that shifts phase by inserting a subsidiary pattern of less than resolution around the pattern, a peripheral shifter mask that improves only the pattern edges by forming shifters around all patterns, without chrome Increase the transmittance of the chromeless phase shifting mask and light-blocking part using the principle that the amount of light at the interface of the phase shifter is zero from "0" to a value other than "0", and phase out other parts. Halftone phase shifting or subtraction with the effect of inverting and canceling each other Phase shift: Attenuated Phase Shifting) may be a mask or the like.

Among the above-described phase inversion masks, masks that can be effectively applied to the ling-space repeating pattern and the contact hole pattern in particular are known as the peripheral effect enhancement and halftone phase inversion masks, and these masks have special phase shifts. It is the most usable phase inversion mask because it does not require a pattern. However, the peripheral effect-enhanced phase inversion mask has difficulty in controlling the size of the rim shifter, and the halftone type phase inversion mask has a disadvantage in that the light transmittance of the halflon region must be precisely adjusted.

The present invention relates to a halftone mask and a method of manufacturing the same among the above-described phase inversion masks. The halftone phase inversion mask is described in T.Terasawa et, al, "Imaging characteristics of muti-phase-shifting and halftone phase-shifting masks", Jap. J. AppI. Phys., Vo1 30, No 11B (1991). ), page 2991 and US Pat. No. 4,890,309, "lithography mask with a" Pi "-phase-shifting attenuator".

First, FIG. 1 is sectional drawing which shows an example of the conventional halftone type phase inversion mask.

In Fig. 1, the halftone phase inversion mask is largely composed of the substrate 1, the halftone pattern 2 and the phase shifter 3 having a transmittance of 0.1-0.2. Typically the halftone pattern is formed of very thin chromium. In addition, the phase shifter 3 formed on the upper surface of the halftone pattern serves as a phase shifter in which the phase is inverted by 180 degrees with respect to the opening of the mask.

Next, FIG. 2 is a plan view schematically showing an example of a conventional halftone phase inversion mask.

In FIG. 2, a pattern forming region 4 in which a constant pattern is formed in the center of a conventional phase inversion mask and a blind region 5 are provided around the pattern forming region 4. The blind area, also called an opaque ring, is used to prevent light from being transmitted around the reticle during exposure, thereby obtaining a precise pattern on the substrate. The blind region 5 is preferably formed such that the light density is at least 2.8. Also shown is a reticle setting mark (6).

In the above conventional halftone phase inversion mask, as shown in FIGS. 1 and 2, the transmittances of the region where the halftone pattern and the phase shifter are formed and the blind region are 0.1 to 0.2. The transmittance helps to form a precise pattern in the region where the halftone pattern and the phase shifter are formed, but light transmission of the blind region is very difficult to obtain a precise pattern.

Accordingly, an object of the present invention is to provide a halftone phase inversion mask capable of suppressing light transmission by forming a blind region in a double structure or forming a grating pattern in order to solve the above problems.

Another object of the present invention is to provide a suitable manufacturing method of a halftone phase inversion mask in which the above problem is solved.

In order to achieve the above object of the present invention, the present invention is a transparent substrate; A pattern formation region provided at a central portion on the substrate; And a blind region formed on the periphery of the pattern formation region and having no light transmission in a double stacked structure of a phase shifter and a light shielding pattern.

The blind area may be formed as a double stacked structure of a phase shifter and a light shielding pattern to suppress light transmission, or may be formed as a grating pattern of a repetitive line-space or checker board to prevent light from being transmitted.

In addition, a specific type of the present invention, the substrate having a plurality of patterns in the form of irregularities in the center portion constant; A halftone pattern formed on a substrate except for a central convex portion of the substrate and a central portion of the substrate; And a light shielding pattern formed on the halftone pattern except for a central portion of the substrate, and through which light is not transmitted.

In addition, the present invention, a plurality of patterns are formed in a predetermined irregular shape in the center portion and a substrate having a plurality of grating patterns in the portion except the center portion; And a halftone pattern formed on the substrate.

The center portion of the substrate is a pattern formation region in which a pattern is formed, and the region except the center portion of the substrate serves as a blind region through which light is not transmitted.

In addition, the grating pattern is formed of a line-space or a checker board to prevent light from being transmitted, provided below a limit resolution of the exposure apparatus, and a pitch of the mask is formed to 1.0 μm or less.

In addition, to achieve the above object of the present invention, the present invention comprises the steps of sequentially forming a halflon layer and a light shielding layer on a transparent substrate; Patterning the light blocking layer to form a light blocking pattern having an opening at a central portion of the substrate; Etching a halflon layer formed on a lower surface of the opening to form a plurality of halftone patterns; And etching a substrate on the lower surface of the halftone pattern to form a phase shifter.

In another aspect, the present invention, forming a halflon layer on a transparent substrate; Patterning the halflon layer to simultaneously form a plurality of halftone patterns in a central portion of the substrate and a grating pattern around them; And forming a phase shifter by etching the substrate on the lower surface of the halftone pattern and the grating pattern, thereby forming a phase shifter.

The grating pattern is formed of a line-space or checker board so that light does not penetrate. In particular, the grating pattern is formed to have a small size below the limit resolution of the exposure apparatus, and preferably, the pitch of the mask is set to 1.0 μm or less.

Accordingly, the halftone phase inversion mask of the present invention can form a blind region in a double stacked structure of a light shielding layer and a halflon layer or form a grating pattern to suppress light transmission during exposure to obtain a precise pattern on a substrate.

Hereinafter, an Example is given and this invention is demonstrated more concretely.

3 and 4 are cross-sectional views showing halftone phase inversion masks according to the present invention.

First, FIG. 3 is a cross-sectional view in which the blind regions a and c are formed in a double stacked structure.

In FIG. 3, the blind regions a and c and the pattern forming region b may be largely divided as shown in FIG. 2. Specifically, a pattern in which the substrate is etched in the form of a U-groove is formed in the center portion, and a halftone pattern 20a is provided on the substrate. A light shielding pattern is formed on the halftone pattern except for the pattern formation region b to provide a blind region which is a feature of the present invention. Here, the halflon layer is formed of MoSi, and the light blocking layer is formed of chromium. The blind regions a and c have a light density of 2.8 or more so that light is not transmitted. The shifter is etched by a depth capable of inverting the substrate itself (d = λ / 2 (n-1), n is the refractive index of the shifter, d is the thickness of the shifter, and λ is the wavelength used). .

Next, FIG. 4 is a cross-sectional view in which grating patterns are formed in blind regions d and f through which light is not transmitted.

In Fig. 4, as shown in Figs. 2 and 3, the phase inversion mask is composed of a pattern formation region e and a blind region d and f in which a pattern is provided. Specifically, the substrate itself is etched in the pattern formation region e to provide a pattern of irregularities, and a pattern of irregularities is also provided in the blind region around it. In addition, a halftone pattern is provided on a substrate having a pattern of the uneven shape.

In particular, the present invention forms a pattern formed in the blind area as a grating pattern of a repetitive line-space or checker board so that light is not transmitted. In addition, the grating pattern is formed to be smaller than the limit resolution of the exposure apparatus, preferably, the pitch of the mask is formed to 1.0㎛ or less.

Hereinafter, the manufacturing method of the phase inversion mask of this invention shown to the said FIG. 3 and FIG. 4 is demonstrated.

5A to 5D are cross-sectional views for explaining a method of manufacturing the halflon phase inversion mask shown in FIG.

FIG. 5A illustrates a step of sequentially forming the halflon layer 20 and the light blocking layer 30 on the transparent substrate 10.

First, the transparent substrate 10 is prepared. In the present invention, glass is used as the material of the substrate 10. The halflon layer 20 is formed on the transparent substrate 10 using MoSi ₂ . The halflon layer 20 is formed to have a transmittance of 10-20% by sputtering or chemical vapor deposition (CVD).

Next, the light blocking layer 30 is formed on the halflon layer 20, and the light blocking layer 30 is formed of chromium, and is formed to have a thickness of 1000 GPa or more by sputtering or chemical vapor deposition (CVD). .

5B illustrates a step of patterning a photoresist film in order to pattern the formed light blocking layer 30.

After the step of FIG. 5A, a photoresist film is applied on the light shielding layer 30, an area where an opening is to be formed is exposed by using an electron beam, and the exposed photoresist film is developed to form a photoresist pattern 40.

5C illustrates a step of forming the light shielding pattern 30a by patterning the light shielding layer 30.

First, the light blocking layer 30 is anisotropically etched using the photoresist pattern 40 as an etching mask to form a light blocking pattern 30a having an opening. Anisotropic etching of the light shielding layer 30 may be performed by a wet etching method using a chromium etchant, or by a dry etching method using a plasma method using a Cl ₂ + O ₂ based gas.

In the etching of the light blocking layer 30, the half-tone layer 20 and the light blocking layer 30 may be formed of different materials, thereby allowing a certain level of etching selectivity to be secured, and thus etching time point detection and etching termination may be performed.

Next, a photoresist is applied and patterned again on the light shielding pattern 30a and the halflon layer 20 to form a second photoresist pattern 50, wherein the second photoresist pattern 50 is a pattern of a pattern formation region. And an etch mask for forming a halftone pattern.

5d illustrates a step of forming the shifter and the halftone pattern 20a.

Using the second photoresist pattern 50 as an etching mask, the halflon layer and the substrate are sequentially anisotropically etched. The etched substrate serves as a phase shifter, and the etching depth is formed to be lambda / 2 (n-1).

The half-layered phase inversion mask of the double layered structure described above enables the half-tone layer and the light-shielding layer to be formed of different materials, thereby ensuring a certain level of etching selectivity, and thus allowing endpoint detection and etching termination during the light-shielding layer etching. In addition, the light shielding material is used to suppress the transmission of light in the blind area of the half-lon phase reversal mask.

6A to 6C are cross-sectional views illustrating a method of manufacturing the half-lon phase inversion mask shown in FIG. 4.

FIG. 6A illustrates forming the halflon layer 110 on the transparent substrate 100.

First, the transparent substrate 10 is prepared. In the present invention, glass is used as the material of the substrate 10. The halflon layer 110 is formed on the transparent substrate 100 using MoSi ₂ or Cr. The halflon layer is formed to have a transmittance of 10-20% by sputtering or chemical vapor deposition (CVD).

6B illustrates a step of patterning a photoresist film in order to pattern the formed halflon layer 110.

After the step of FIG. 5A, a photoresist film is coated on the halflon layer 110, an area where an opening is to be formed by using an electron beam is exposed, and the exposed photoresist film is developed to form a photoresist pattern 120. The photoresist layer pattern 120 is simultaneously formed in the pattern formation region (e of FIG. 6c) and the blind region (d, f of FIG. 6c) around the center portion of the substrate 100.

FIG. 6C shows forming the shifter, the halftone pattern and the pattern on the blind area.

First, the light blocking layer 30 is anisotropically etched using the photoresist pattern 120 as an etching mask to form a pattern 110a in a request form. The pattern 110a may be divided into a halftone pattern provided in the pattern formation region e of the center portion of the substrate 100 and a grating pattern provided in the blind regions d and f around the substrate 110. In particular, the grating pattern formed in the blind area is formed in a pattern of a repetitive line-space or checker board so that light is not transmitted. In addition, the grating pattern is formed to be smaller than the limit resolution of the exposure apparatus, preferably, the pitch of the mask is formed to 1.0㎛ or less.

Subsequently, the substrate is anisotropically etched using the photoresist pattern 120 as an etch mask. The etched substrate serves as a phase shifter, and the etching depth is formed to a depth of λ / 2 (n-1) so that the phase is inverted by 180 degrees to obtain a halftone phase inversion mask.

The halftone phase inversion mask is formed by forming a blind region in a double stacked structure of a light shielding layer and a halflon layer or forming a grating pattern to suppress light transmission during exposure to obtain a precise pattern on a substrate.

As mentioned above, although this invention was demonstrated concretely, this invention is not limited to this, A deformation | transformation and improvement are possible in the range of the common knowledge of a person skilled in the art.

Claims (9)

Transparent substrates; A pattern formation region provided at a central portion on the substrate; And a blind region formed on a substrate around the pattern formation region and in which light is not transmitted in a double stacked structure of a phase shifter and a light shielding pattern. The halftone phase inversion mask of claim 1, wherein the blind area is in a grating pattern of a repetitive line-space or checker board. A substrate having a plurality of patterns in a concave-convex shape constantly in the center portion; A halftone pattern formed on a substrate except for a central convex portion of the substrate and a central portion of the substrate; And a light shielding pattern formed on the halftone pattern except for a central portion of the substrate and to which light is not transmitted. A substrate having a plurality of patterns uniformly formed in a concave-convex shape in the center portion and a plurality of grating patterns in portions except the center portion; And a halftone pattern formed on the substrate. The half-tone phase inversion according to claim 3 or 4, wherein the center portion of the substrate is a pattern formation region in which a pattern is formed, and the region except the center portion of the substrate is a blind region through which light is not transmitted. Mask. The halftone phase shift mask according to claim 4, wherein the grating pattern is formed of a line-space or a checker board, and the size of the grating pattern is smaller than the limit resolution of the exposure apparatus. 7. The halftone phase reversal mask according to claim 6, wherein the size of the limit resolution or less is that the mask pitch is 1.0 mu m or less. Sequentially forming a halflon layer and a light shielding layer on the transparent substrate; Patterning the light blocking layer to form a light blocking pattern having an opening at a central portion of the substrate; Etching a halflon layer formed on a lower surface of the opening to form a plurality of halftone patterns; And etching a substrate on the lower surface of the halftone pattern to form a phase shifter. Forming a halflon layer on the transparent substrate; Patterning the halflon layer to simultaneously form a plurality of halftone patterns in a central portion of the substrate and a grating pattern around them; And etching a substrate on the lower surface of the halftone pattern and the grating pattern to form a phase shifter.