TWI682234B - Phase-shift blankmask and phase-shift photomask - Google Patents

Abstract

Disclosed are a phase-shift blankmask and a phase-shift photomask, which includes a phase-shift film made of silicon (Si) or a silicon (Si) compound on a transparent substrate and has a high transmittance characteristic. In the phase-shift blankmask according to the present disclosure, the phase-shift film has a high transmittance of 50% or higher, thereby achieving a micro pattern smaller than or equal to 32 nm, preferably 14 nm, and more preferably 10 nm for a semiconductor device, for example, a DRAM, a flash memory, a logic device.

Description

Phase shift blank mask and phase shift mask

[Cross reference to related applications]

This application requires the priority of Korean Patent Application No. 10-2017-0061699 filed with the Korean Intellectual Property Office on May 18, 2017 and Korean Patent Application No. 10-2018-0048241 filed on April 26, 2018, Its disclosure is incorporated herein by reference.

The present invention relates to a phase shift blank mask and a phase shift mask, and more specifically to such a phase shift blank mask and a phase shift mask, wherein the phase shift film has more than 50% of the exposure wavelength High transmittance, which improves the margin of depth of focus and exposure latitude during wafer exposure.

At present, advanced semiconductor micro-manufacturing technology has become very important, which can meet the requirements of high integration of large integrated circuits and miniaturization of circuit patterns. In the case of semiconductor integrated circuits, there is an increasing demand for miniaturization of circuit wiring for high-speed operation and low power consumption, contact hole patterns for interlayer connection, and circuit arrangements corresponding to integration increase.

As such, due to the high integration of miniaturized patterns, the resolution and pattern registration standards required by the reticle have become more stringent. In addition, as the core problem of manufacturing semiconductor devices, there is an increasing need to ensure the depth of focus limit and exposure latitude in the process of manufacturing complex multilayer semiconductor devices.

This problem is not only affected by the manufacturing process of the photomask and the semiconductor device, but also by the characteristics of the blank mask as a key part of manufacturing the semiconductor device. For example, when manufacturing a semiconductor device using a photomask formed by a phase shift blank mask, high resolution is achieved with high image contrast, and the depth of focus limit is improved.

Recently, due to the need for higher precision and smaller semiconductor devices, a phase shift blank mask has been developed, which includes a phase shift film with a transmittance of 12%, 18%, 24%, or 30%. The transmission of the phase shift film The rate is higher than the transmittance of the existing phase shift film (6%). Compared with the existing phase shift mask with 6% transmittance, the phase shift mask with such high transmittance has the effect of making the focal depth limit and exposure latitude greater.

At the same time, as another phase shift mask technology for realizing a phase shift pattern with high transmittance, it is used for chromless phase-shift lithography (CPL) for forming a phase shift pattern by etching a transparent substrate The phase-shift blank mask has attracted attention. Specifically, the CPL phase shift mask is formed with a phase shift pattern of about 100% transmittance and a phase degree of 180°. After forming a light shielding film and a resist film pattern on a transparent substrate, the light shielding is formed by an etching process A film pattern, and the transparent substrate is etched at a predetermined depth by using a light-shielding film pattern as an etching mask, thereby obtaining a phase shift pattern as a phase shift portion.

However, due to the etching process tool for forming the transparent substrate of the phase shift pattern There are the following problems, so the use of CPL phase shift blank masks is restricted.

First of all, it is difficult for the CPL phase shift mask to clearly identify the etching end point, because there is no thin film layer for identifying the etching end point with respect to the transparent substrate, and there is no difference in the detection amount of a specific material while etching the substrate. Generally, the etching end point of the thin film is detected based on the difference in the detection amount between the metal contained in the thin film and light elements including nitrogen (N), oxygen (O), and carbon (C). However, since the specific material does not change, it is difficult to detect the etching end point of the transparent substrate. Therefore, because the etching of the transparent substrate depends on the etching time, the phase shift portion formed by etching the transparent substrate causes problems such as low resolution, and thus it is difficult to ensure the reproducibility of the phase power and it is difficult to control the etching.

In addition, since the transparent substrate has high hardness due to the high-temperature heat treatment process, it is difficult to repair defects caused when the transparent substrate is etched. Therefore, even if the CPL screen has excellent characteristics, it is rarely mass-produced and used.

Therefore, an aspect of the present disclosure is to provide a phase shift blank mask and a phase shift photomask, in which a phase shift film having a high transmittance of 50% or more is used.

Another aspect of the present disclosure is to provide a phase-shift blank mask and a phase-shift photomask, in which a resist film can be made into a thin film and improved in resolution, critical dimensional accuracy, and linearity.

Another aspect of the present disclosure is to provide a phase-shift blank mask and a phase-shift photomask, which can achieve about 32 nm or less, especially about 14 nm for various semiconductor devices The following micropattern.

According to an embodiment of the present disclosure, there is provided a phase shift blank mask having a phase shift film provided on a transparent substrate, wherein the phase shift film is etched using the same material as the transparent substrate, and the phase shift film contains detectable The material relative to the etching end point of the transparent substrate.

For exposure light, the phase shift film may have a transmittance of more than 50%.

The phase shift film may contain silicon (Si) or silicon (Si) compounds.

The material for detecting the etching end point may include nitrogen (N).

A light-shielding film may be further provided on the phase shift film.

The light-shielding film may contain one of chromium (Cr), chromium (Cr) compounds, molybdenum chromium (MoCr), and molybdenum chromium (MoCr) compounds.

A hard mask film may be provided on the light-shielding film and the phase shift film that are sequentially stacked.

The hard mask film may include a material having the same etching properties as the phase shift film and having the same etching selectivity as the light shielding film.

A resist film may be further provided on the phase shift film, and a charge dissipation layer may be further provided on the resist film.

The charge dissipation layer may include a self-doped water-soluble conductive polymer.

100, 200, 300 ‧‧‧ phase shift blank mask

102、202‧‧‧Transparent substrate

104, 204‧‧‧ phase shift film

106, 206‧‧‧ shading film

110、210‧‧‧resist film

112, 212‧‧‧ charge dissipation layer

204a‧‧‧Phase shift film pattern

206a‧‧‧shading film pattern

208‧‧‧hard cover film

208a‧‧‧hard mask pattern

210a‧‧‧resist film pattern

214a‧‧‧Second resist film pattern

The above and/or other aspects will become clear and easier to understand through the following description of exemplary embodiments in conjunction with the accompanying drawings, in which: 1 is a cross-sectional view of a phase-shift blank mask with high transmittance according to the first structure of the present disclosure; FIG. 2 is a cross-sectional view of a phase-shift blank mask with high transmittance according to the second structure of the present disclosure; 3A and 3B are cross-sectional views of a phase-shift blank mask with high transmittance according to the second structure of the present disclosure; and FIGS. 4A to 4E are used to explain the manufacturing of the second structure with high transmittance according to the present disclosure A cross-sectional view of the method of rate-shifting the blank mask.

Hereinafter, embodiments of the present invention will be described in more detail with reference to the drawings. However, these embodiments are provided for illustrative purposes only, and should not be construed as limiting the scope of the present invention. Therefore, those of ordinary skill in the art will understand that various modifications and equivalent transformations can be made from these embodiments. Furthermore, the scope of the invention must be defined in the appended claims.

FIG. 1 is a cross-sectional view of a phase-shift blank mask with high transmittance according to the first structure of the present disclosure.

Referring to FIG. 1, a phase shift blank mask 100 according to the present disclosure includes a transparent substrate 102, and a phase shift film 104, a light shielding film 106, and a resist film 110 that are sequentially formed on the transparent substrate 102.

The transparent substrate 102 includes quartz glass, synthetic quartz glass, or fluorine-doped quartz glass. The flatness of the transparent substrate 102 affects one of the thin films formed thereon, such as the phase shift film 104 or the light-shielding film 106, and affects the depth of focus limit during wafer exposure. Therefore, when the flatness of the surface on which the film is grown is defined as a total indicated reading (TIR) value, within a measurement area of 142 mm ² , the value is controlled to be less than or equal to 1,000 nm, preferably It is lower than or equal to 500 nm, and more preferably lower than or equal to 300 nm to obtain good flatness.

The phase shift film 104 may include one or more selected from the following materials: silicon (Si), molybdenum (Mo), tantalum (Ta), vanadium (V), cobalt (Co), nickel (Ni), zirconium (Zr) , Niobium (Nb), palladium (Pd), zinc (Zn), chromium (Cr), aluminum (Al), manganese (Mn), cadmium (Cd), magnesium (Mg), lithium (Li), selenium (Se) , Copper (Cu), hafnium (Hf) and tungsten (W), or in addition to the above materials, it also contains one or more of light elements, the light elements include nitrogen (N), oxygen (O), carbon (C ), boron (B) and hydrogen (H).

In particular, the phase shift film 104 may include a compound of silicon (Si) to achieve high transmittance. Specifically, the phase shift film 104 may include silicon (Si) or silicon (Si) compounds selected from SiN, SiC, SiO, SiCN, SiCO, SiNO, SiCON, SiB, SiBN, SiBC, One or more materials of SiBO, SiBCN, SiBCO, SiBNO, and SiBCON, these silicon compounds contain oxygen (O), nitrogen (N), carbon (C), and boron (B) in addition to silicon (Si) One or more light elements.

The phase shift film 104 has a transmittance of 50% or more, preferably 70% or more, or more preferably 90% or more with respect to the exposure wavelength of 193 nm. According to an aspect of the present disclosure, the phase shift film 104 contains a silicon (Si) compound, and particularly contains a silicon (Si) compound containing oxygen (O) to have a high transmittance of 50% or more. Silicon (Si) compound Increasing the content of oxygen (O) in the medium will decrease the refractive index (n) and extinction coefficient (k) of the phase shift film, thereby ultimately increasing the transmittance and thickness of the phase shift film.

However, during wafer exposure, an increase in the transmittance of the phase shift film 104 improves destructive interference at the edges of the pattern, but the increased thickness increases the aspect ratio of the pattern during the mask manufacturing process, and thus leads to The pattern collapses. Therefore, the oxygen (O) content in the phase shift film 104 is appropriately controlled to adjust the transmittance and thickness of the phase shift film. For example, when manufacturing a high transmittance phase shift mask to form a 100 nm dot pattern, the thickness of 200 nm can be formed by increasing the content of oxygen (O) in order to maintain the aspect ratio of the pattern to 2 or less and achieve a height of 90% or more Transmittance. In addition, in order to have the same pattern aspect ratio of 2 or less while forming a 70 nm dot pattern, the thin film must have a thickness of 140 nm or less. In this case, in order to control the phase amount, a phase shift film having a transmittance of 70% can be manufactured by relatively reducing the oxygen (O) content or increasing the nitrogen content (N).

In addition, the contents of oxygen (O) and nitrogen (N) in the above-mentioned phase shift film 104 must be appropriately controlled because the contents of oxygen (O) and nitrogen (N) are also used for the purpose of detecting the etching end point during etching. For example, when the content of oxygen (O) in the phase shift film 104 is high, it is difficult to detect the etching end point with respect to the lower transparent substrate 102. Therefore, in order to detect the etching end point of the phase shift film 104, in addition to oxygen (O), light elements such as nitrogen (N), carbon (C), etc. may be included. Preferably, nitrogen (N) may be included to facilitate the detection of the etching end point. However, when the content of nitrogen (N) contained in the phase shift film 104 is high, the transmittance of the phase shift film 104 to the exposure wavelength decreases. Therefore, it is necessary to properly control The content of oxygen (O) and the content of light elements such as nitrogen (N) are such that the phase shift film 104 has high transmittance and easily determines the etching end point.

In order to satisfy the above-mentioned characteristics, the phase shift film 104 may have a composition ratio including 10 atomic% to 40 atomic% silicon (Si) and 60 atomic% to 90 atomic% light elements (ie, N, O, C, etc.) sum). In particular, the content of nitrogen (N) in the light element contained in the phase shift film 104 is 1 atomic% to 20 atomic %, preferably 3 atomic% to 20 atomic %. When the nitrogen (N) content is 1 atomic% or less, it is difficult to detect the etching end point with respect to the lower transparent substrate 102. When the nitrogen (N) content is 20 atomic% or more, it is difficult to ensure high transmittance of the phase shift film 104.

The content of oxygen (O) in the light element contained in the phase shift film 104 may be 50 atomic% to 90 atomic %. When the content of oxygen (O) is less than or equal to 50 atomic %, it is difficult to ensure high transmittance of the phase shift film 104. When the content of oxygen (O) is equal to or higher than 90 atomic %, it is difficult to detect the etching end point with respect to the lower transparent substrate 102.

The phase shift film 104 is formed through a sputtering process, and a silicon (Si) target or a boron (B) doped silicon (Si) target can be used in the sputtering process to enhance sputtering conductivity during sputtering. In this case, the resistivity of the boron (B) doped silicon (Si) target is 1.0E-04Ω.cm to 1.0E+01Ω.cm, preferably 1.0E-03Ω.cm to 1.0E-02Ω. cm. When the resistivity of the target is high, abnormal discharges such as arcs may occur during sputtering, resulting in defects in thin film characteristics.

The phase shift film 104 can be produced by using one or more gases selected from reactive gases such as nitric oxide (NO), nitrogen dioxide (NO ₂ ), carbon dioxide (CO ₂ ), etc. during the sputtering process Oxygen (O).

In addition, a silicon (Si) target for forming the phase shift film 104 can be manufactured by a columnar crystal method or a single crystal method.

In order to minimize the defects of the thin film during sputtering, the content of impurities in the target can be controlled. For this reason, the content of impurities in the silicon (Si) target, especially the content of carbon (C) and oxygen (O) may be lower than or equal to 30 ppm, and preferably lower than or equal to 5.0 ppm. The content of other impurities (for example, Al, Cr, Cu, Fe, Mg, Na, and K) other than carbon (C) and oxygen (O) may be lower than or equal to 1.0 ppm, and preferably lower than or equal to 0.05 ppm. In addition, when these impurities are controlled so that the purity of the manufactured target is equal to or higher than 4N, preferably equal to or higher than 5N, defects can be well controlled.

The phase shift film 104 has one of the following structures, for example: a single-layer film having a uniform composition; a single-layer continuous film in which the composition or composition ratio continuously changes; and a multilayer film in which one or more films of different composition or composition ratio are stacked For one or more layers.

The thickness of the phase shift film 104 may be 1,000 Å to 2,000 Å, and preferably 1,100 Å to 1,800 Å, and for exposure light with a wavelength of 193 nm, the phase power is 170° to 240°, preferably 180° to 230°, and more It is preferably 190° to 220°. In addition, the phase shift film 104 has a reflectance of 20% or less for all wavelengths from 190 nm to 1,000 nm.

The phase shift film 104 may be heat-treated at a temperature of 100°C to 1,000°C to release the film stress caused when the film is formed. The heat treatment process can use vacuum rapid heat treatment device, furnace or hot plate. In addition, the heat treatment process is performed in a gas atmosphere containing oxygen (O) or nitrogen (N), so that the characteristics of the film surface can be improved, For example, resistance to chemicals used in cleaning.

When the film stress is defined as TIR, the phase shift film 104 is manufactured so that the rate of change of TIR before and after film growth is 300 nm or less, preferably 200 nm or less.

The light-shielding film 106 may have various structures, such as a single-layer film, a continuous film, and a multi-layer film including two or more layers (such as a first light-shielding layer and a second light-shielding layer), and may include such materials when the phase shift When the film 104 is dry-etched, the etching selectivity of the material is equal to or higher than 10.

The light-shielding film 106 may include one or more selected from the following materials: molybdenum (Mo), tantalum (Ta), nickel (Ni), zirconium (Zr), niobium (Nb), palladium (Pd), zinc (Zn), Selenium (Se), chromium (Cr), aluminum (Al), manganese (Mn), cadmium (Cd), magnesium (Mg), lithium (Li), selenium (Se), hafnium (Hf) and tungsten (W), Or in addition to the above materials, it also contains one or more of the following light elements: nitrogen (N), oxygen (O), and carbon (C). Specifically, the light-shielding film 106 may contain a metal compound containing chromium (Cr). When the light-shielding film 106 contains a chromium (Cr) compound, its composition ratio is: chromium (Cr) is 30 atom% to 70 atom%, nitrogen (N) is 10 atom% to 40 atom%, and oxygen (O) is 0 to 50 atomic %, and carbon (C) is 0 to 30 atomic %.

The light-shielding film 106 may contain a compound containing chromium (Cr) and molybdenum (Mo), wherein the content of molybdenum (Mo) increases the etching rate and the extinction coefficient, so the light-shielding film 106 can be made into a thin film. In this case, the compound can be realized by one of the molybdate chromate (MoCr) compounds, the composition ratio of the molybdate chromate compound is: molybdenum (Mo) is 2 atom% to 30 atom%, chromium (Cr) 30 atomic% to 60 atomic %, nitrogen (N) is 10 atomic% to 40 atomic %, oxygen (O) is 0 to 50 atomic %, and carbon (C) is 0 to 30 atomic %.

The thickness of the light-shielding film 106 is 500Å to 1,000Å, preferably 500Å to 800Å.

In addition, although not shown, an anti-reflection film for preventing reflection of exposure light may be additionally provided on the light-shielding film 106, and the anti-reflection film may have the same etching properties or the same etching selectivity as the light-shielding film 106 Made of materials.

The optical density of the thin film on which the phase shift film 104 and the light-shielding film 106 are laminated is 2.5 to 3.5, preferably 2.7 to 3.2, and for exposure light with a wavelength of 193 nm, the surface reflectance is 10% to 40%, preferably 20% to 35%.

The light-shielding film 106 may be selectively heat-treated. In this case, the heat treatment temperature may be lower than or equal to the heat treatment temperature of the phase shift film 104 located below.

2 is a cross-sectional view of a phase-shift blank mask with high transmittance according to the second structure of the present disclosure.

Referring to FIG. 2, a phase shift blank mask 200 with high transmittance according to the present disclosure includes a transparent substrate 202 and a phase shift film 204, a light shielding film 206, a hard mask film 208, and a resist film formed on the transparent substrate 202 in sequence 210. Here, the transparent substrate 202, the phase shift film 204, and the light-shielding film 206 are equivalent to the transparent substrate, phase shift film, and light-shielding film in the first structure according to the present disclosure.

The hard mask film 208 is formed on the light shielding film 206, and serves as an etching mask when the light shielding film 206 is patterned. Therefore, the hard mask 208 is located below The etching selectivity of the light-shielding film 206 may be equal to or higher than 10.

The hard mask film 208 may include a material having the same etching properties as the phase shift film 204 to simplify the manufacturing process of the photomask, and the patterned hard mask film 208 is removed during the etching process for patterning the phase shift film 204.

Therefore, the hard mask film 208 may include, for example, one of the following: silicon (Si); silicon (Si) compounds, such as SiN, SiC, SiO, SiCN, SiCO, SiNO, SiCON, SiB, SiBN, SiBC, SiBO, In addition to silicon (Si), SiBCN, SiBCO, SiBNO, and SiBCON contain one or more light elements of oxygen (O), nitrogen (N), and carbon (C); molybdenum silicide (MoSi); and molybdenum silicide ( MoSi) compounds such as MoSiN, MoSiC, MoSiO, MoSiCN, MoSiCO, MoSiNO, and MoSiCON.

The thickness of the hard mask film 208 is 20Å to 200Å, and preferably 50Å to 150Å. The etching rate of the hard mask film 208 is lower than or equal to 10Å/sec.

The resist film 210 formed on the hard mask film 208 may use a positive-type or negative-type chemically amplified resist. The thickness of the resist film 210 is 400Å to 1,500Å, preferably 600Å to 1,200Å.

Although not shown, hexamethyldisilazane (HMDS) may be selectively coated to improve the adhesion between the resist film 210 and the underlying film.

3A and 3B are cross-sectional views of a phase-shift blank mask with high transmittance according to the second structure of the present disclosure.

3A and 3B, a phase shift with high transmittance according to the present disclosure The blank mask 300 includes charge dissipation layers (CDL) 112 and 212, which are formed on the resist films 110 and 210 according to the first structure and the second structure, respectively. Here, the transparent substrates 102 and 202, the phase shift films 104 and 204, the light shielding films 106 and 206, and the hard mask film 208 are equivalent to those in the first structure and the second structure according to the present disclosure.

The charge dissipation layers 112 and 212 may be selectively formed on the resist film, and may include a self-doped water-soluble conductive polymer having characteristics soluble in deionized (DI) water. With this structure, the charge-up phenomenon of electrons during exposure can be prevented, and the resist films 110 and 210 are prevented from being thermally deformed due to the charge phenomenon.

The thickness of the charge dissipation layers 112 and 212 may be 5 nm to 60 nm, preferably 5 nm to 30 nm.

As described above, the present invention uses a phase shift reticle including a phase shift film, which has a high transmittance of more than 50% for the exposure wavelength, and therefore not only improves the resolution, but also improves the crystal during the semiconductor device manufacturing process. The depth of focus limit and exposure latitude during circular exposure increase the process yield.

In addition, the present disclosure employs a hard mask film when forming a pattern, thereby making the resist film into a thin film and thus improving resolution, critical dimensional accuracy, and linearity.

In addition, the present disclosure uses a phase-shift blank mask with high transmittance to increase the process window, thus improving the manufacture of various semiconductor devices (eg, dynamic random access memory (DRAM), flash memory, logic Devices, etc.) during the process yield yield.

Hereinafter, the phase shift blank mask will be described in detail according to the embodiments of the present disclosure.

implementation plan

Embodiment 1: A method for manufacturing a blank mask and a photomask (transmittance is about 70% PSM)

This embodiment will be described with reference to FIGS. 4A to 4E to describe a method of manufacturing a phase-shift blank mask curtain and a photomask with high transmittance according to the second structure of the present disclosure.

Referring to FIG. 4A, a phase shift film 204, a light-shielding film 206, a hard mask film 208, and a resist film 210 are sequentially formed on the transparent substrate 202.

The transparent substrate 202 has a concave shape, and when its flatness is defined as TIR, its TIR value is -82 nm.

By injecting a process gas of Ar:N ₂ :NO=5sccm:5sccm:5.3sccm into a single wafer direct current (DC) magnetron sputtering device mounted with a boron (B) doped silicon (Si) target, and A process power of 1.0 kW was applied to manufacture a SiON film as a phase shift film 204 by a columnar crystal method, with a purity of 6N and a thickness of 125 nm.

The transmittance and phase power of the phase shift film 204 were measured through the n&k Analyzer 3700RT. With respect to the wavelength of 193 nm, the center value of the transmittance was 68%, and the center value of the phase power was 205°. In addition, the convex value (convex value) was measured as the flatness, and the convex value was +80 nm. In addition, the composition ratio of the phase shift film 204 was analyzed by AES, and the composition ratio of silicon (Si): nitrogen (N): oxygen (O) was 16.3 atomic %: 15.6 atomic %: 68.1 atomic %.

Then, in order to improve the flatness, the phase shift film 204 is subjected to a heat treatment at a temperature of 500° C. for 40 minutes through a vacuum rapid heat treatment device. By measuring the phase shift As for the stress of the film 204, the convex value is +30 nm, and the stress change (ie, delta stress) of the entire phase shift film 204 is +112 nm. This means that stress is released through heat treatment.

The light-shielding film 206 is manufactured as follows: by injecting a process gas of Ar:N ₂ :CH ₄ =5 sccm:12 sccm:0.8 sccm into a single-wafer type DC magnetron sputtering device mounted with a chromium (Cr) target, and applying 1.4 kW Process power, thereby producing an underlying film CrCN with a thickness of 43 nm. Then, by injecting a process gas of Ar:N ₂ :NO=3 sccm:10 sccm:5.7 sccm, and applying a process power of 0.62 kW, an upper layer CrON with a thickness of 16 nm is manufactured, thereby manufacturing a double-layer structure.

Then, the optical density and reflectance of the light-shielding film 206 were measured, and as a result, the light-shielding film 206 showed an optical density of 3.10 and a reflectance of 29.6% for exposure light having a wavelength of 193 nm. This means that there is no problem in using the manufactured light-shielding film as the light-shielding film 206.

By injecting a process gas of Ar:N ₂ :NO=7sccm:7sccm:5sccm into a single crystal DC magnetron sputtering device mounted with a silicon (Si) target, and applying a process power of 0.7kW, a thickness of 10nm was produced The SiON film serves as the hard mask film 208.

Next, HMDS is coated on the hard mask film 208, and then a negative-type chemically amplified resist having a thickness of 100 nm is formed through a spin coating system, thereby completely manufacturing a phase shift blank mask.

After the blank mask manufactured as described above is subjected to an exposure process, post exposure bake (PEB) is performed at a temperature of 100° C. for 10 minutes, and developed to form a resist film pattern 210a.

Then, using the resist film pattern 210a as an etching mask, the underlying hard mask film is subjected to fluorine-based dry etching to form a hard mask film pattern 208a. In this case, the hard mask was measured through an end point detection (EPD) system, and the result was 17 seconds.

Referring to FIG. 4B, the resist film pattern is removed, and then the hard mask film pattern 208a is used as an etching mask to etch the lower light shielding film, thereby forming the light shielding film pattern 206a. Alternatively, the light-shielding film may be etched using a resist film and a hard mask film as etching masks.

Referring to FIG. 4C, a hard mask film pattern 208a and a light-shielding film pattern 206a are used as etching masks to apply fluorine-based dry etching to the phase shift film below, thereby forming a phase shift film pattern 204a.

In this case, by analyzing the etching end point of the phase shift film pattern 204a through the EPD system, the etching end point relative to the lower transparent substrate 202 can be identified by using a nitrogen (N) peak. Here, when etching is performed to form the phase shift film pattern 204a, the hard mask film pattern 208a is completely removed.

Referring to FIGS. 4D and 4E, a second resist film pattern 214a is formed on the transparent substrate 202 on which the phase shift film pattern 204a is formed, and then the light-shielding film pattern 206a of the main exposed area except the peripheral area is removed to complete Manufacturing phase shift masks.

Regarding the phase shift mask manufactured as described above, MPM-193 was used to measure the pure transmittance and phase power of the phase shift film pattern. As a result, the transmittance at a wavelength of 193 nm was 72.3%, and the phase degree was 215°. In addition, using TEM for measurement, the pattern profile was measured to be 86°.

Embodiment 2: A method for manufacturing a blank mask and a photomask (transmittance is about 100% PSM)

In this embodiment, such a phase shift reticle is manufactured, and its phase shift film pattern has higher transmittance as compared with Embodiment 1.

First, the same sputtering target and device as in Embodiment 1 were prepared, and a process gas of Ar:N ₂ :NO=5 sccm: 5 sccm:7.1 sccm was injected into the device and a process power of 1.0 kW was applied, thereby forming a thickness of 160 nm Of SiON film.

As a result of measuring the transmittance and phase power of the formed phase shift film 104 through the n&k Analyzer 3700RT, at a wavelength of 193 nm, the transmittance was 87% and the phase power was 204°. In addition, the composition ratio of the phase shift film manufactured above was analyzed by AES, and the composition ratio of silicon (Si): nitrogen (N): oxygen (O) was measured to be 21.2 atomic %: 4.0 atomic %: 74.8 atomic %.

In addition, after stacking the light-shielding film, the hard mask film, and the resist film in sequence as described in Embodiment 1, a phase shift film pattern is manufactured through a photomask process, and the purity of the phase shift film pattern is measured using MPM-193 Transmittance and phase power. As a result, the transmittance was 97.2%, and the phase degree was 213°.

Comparative example: manufacture of substrate etching type phase shift blank mask

In this comparative example, substrate etching type phase shift blank masks and photomasks were manufactured for comparison with Embodiment 1.

First, inject a process gas of Ar:N ₂ :CH4=5sccm:5sccm:0.8sccm into a single crystal DC magnetron sputtering device equipped with a chromium (Cr) target, and apply a process power of 1.4kW to the transparent substrate A substrate etching type blank mask with a thickness of 43 nm as a lower layer film CrCN was fabricated thereon. Then, by injecting a process gas of Ar:N ₂ :NO=3 sccm:10 sccm:5.7 sccm and supplying a process power of 0.62 kW, a CrON film with a thickness of 16 nm is manufactured as an upper layer film, thereby forming a double-layer structure.

Here, the optical density and reflectance of the light-shielding film were measured, and the light-shielding film showed an optical density of 3.05 and a reflectance of 31.2% for exposure light with a wavelength of 193 nm.

Then, a negative-type chemically amplified resist with a thickness of 170 nm was formed on the hard mask film through a spin coating system, thereby completely manufacturing a phase shift blank mask.

Next, a resist film pattern is formed, and then the resist film pattern is used as an etching mask to etch the lower light-shielding film, thereby forming a light-shielding film pattern. Then, the resist film is removed, the light-shielding film pattern is used as an etching mask, and the exposed transparent substrate underneath is etched based on fluorine (F) gas.

In this case, the etching time is set to etch the transparent substrate, and the etched transparent substrate shows a thickness of 200 nm and a phase degree of 220°.

Regarding the phase shift portion of the phase shift mask according to Embodiment 1 and the phase shift portion of the substrate-etched phase shift mask manufactured according to the comparative example, the results of measuring uniformity are listed below.

Referring to Table 1, the difference in transmittance range between Embodiment 1 and Comparative Example is not obvious. On the other hand, the range shown in the phase power according to Embodiment 1 is 1.2°, but the range shown in the phase power according to the comparative example is 8°. Therefore, it can be understood that the substrate etching type phase shift reticle is hardly available.

Regarding the above transmittance and phase power, 5 phase shift masks according to Embodiment 1 and 5 phase shift masks according to Comparative Examples were produced, and the reproducibility test process for measuring the center value thereof was performed. The results are shown in Table 2 below. .

Referring to Table 2, the central values of the transmittance corresponding to the plates between Embodiment 1 and the comparative example are similar to each other, so the difference is slight. On the other hand, Embodiment 1 shows a phase degree of 2°, but the comparative example shows a phase degree of 13°. Therefore, it can be understood that the comparative example is relatively difficult to control the phase degree.

The present disclosure employs a phase shift mask including a phase shift film The wavelength has a high transmittance of more than 50%, so not only by improving the resolution, but also by increasing the depth of focus limit and exposure latitude during wafer exposure during semiconductor device manufacturing, thereby improving the yield yield of the process.

In addition, the present disclosure uses a hard mask film when forming a pattern, thereby making the resist film into a thin film and thus improving resolution, critical dimensional accuracy, and linearity.

In addition, the present disclosure uses a phase-shift blank mask with high transmittance to increase the process window, thus improving the process yield when manufacturing various semiconductor devices (eg, DRAM, flash memory, logic devices, etc.).

Although the present disclosure has been shown and described with exemplary embodiments, the technical scope of the present disclosure is not limited to the scope disclosed in the foregoing embodiments. Therefore, those of ordinary skill in the art will understand that various changes and modifications can be made from these exemplary embodiments. In addition, as defined in the appended claims, it is obvious that these changes and modifications are included in the technical scope of the present disclosure.

200‧‧‧ Phase shift blank mask

202‧‧‧Transparent substrate

204‧‧‧phase shift film

206‧‧‧shading film

208‧‧‧hard cover film

210‧‧‧resist film

Claims (25)

A phase shift blank mask includes a phase shift film provided on a transparent substrate and a light-shielding film provided on the phase shift film, wherein the phase shift film is etched by the same material as the transparent substrate, and the phase The shift film includes a material capable of detecting the etching end point with respect to the transparent substrate, and the light shielding film or the structure in which the light shielding film is stacked on the phase shift film has an optical density of 2.5 to 3.5 for exposure light. The phase shift blank mask as described in item 1 of the patent application range, wherein the phase shift film has a transmittance of more than 50% for exposure light. The phase shift blank mask as described in item 1 of the patent application scope, wherein the phase shift film contains silicon (Si), or a silicon (Si) compound containing one or more light elements in addition to silicon (Si) The silicon (Si) compound is one or more materials selected from SiN, SiC, SiO, SiCN, SiCO, SiNO, SiCON, SiB, SiBN, SiBC, SiBO, SiBCN, SiBCO, SiBNO, and SiBCON. The phase shift blank mask as described in item 3 of the patent application scope, wherein when the phase shift film contains the silicon (Si) compound, its composition ratio is: silicon (Si) is 10 atomic% to 40 atomic% , And the light element is 60 atomic% to 90 atomic %. The phase shift blank mask as described in item 1 of the patent application range, wherein the material capable of detecting the etching end point includes nitrogen (N). The phase shift blank mask as described in item 5 of the patent application range, wherein when the phase shift film contains nitrogen (N), the content of nitrogen (N) is 1 atomic% to 20 atomic %. The phase shift blank mask as described in item 1 of the patent application range, wherein when the phase shift film contains oxygen (O), the content of oxygen (O) is 50 atomic% to 90 atomic %. The phase shift blank mask as described in item 3 of the patent application range, wherein the phase shift film is formed by using a silicon (Si) target or a boron (B) doped silicon (Si) target, and the target The specific resistance is from 1.0E-04Ω.cm to 1.0E+01Ω.cm. The phase shift blank mask as described in item 1 of the patent application scope, wherein the phase shift film has one of the following structures: a single layer film having a uniform composition; a single layer continuous film whose composition or composition ratio changes continuously; and composition Or a multilayer film in which one or more films with different composition ratios are stacked into one or more layers. The phase shift blank mask as described in item 1 of the patent application scope, wherein the thickness of the phase shift film is 1,000 Å to 2,000 Å. The phase shift blank mask as described in item 1 of the patent application scope, wherein the phase degree of the phase shift film is 170° to 240° relative to the exposure light with a wavelength of 193 nm. The phase shift blank mask as described in item 1 of the patent application scope, wherein the light-shielding film comprises one of the following materials: chromium (Cr); chromium (Cr) compound, the composition ratio of which is 30 atoms % To 70 atomic %, nitrogen (N) 10 atomic% to 40 atomic %, oxygen (O) 0 to 50 atomic %, and carbon (C) 0 to 30 atomic %; molybdenum chromium (MoCr); molybdenum chromium (MoCr) compound, its composition ratio is molybdenum (Mo) 2 atom% to 30 atom%, chromium (Cr) 30 atom% to 60 atom%, nitrogen (N) 10 atom% to 40 atom%, oxygen ( O) is 0 to 50 atomic %, and carbon (C) is 0 to 30 atomic %. The phase shift blank mask as described in item 1 of the patent application range, wherein the thickness of the light-shielding film is 500 Å to 1,000 Å. The phase-shift blank mask as described in item 1 of the patent application scope, further includes an anti-reflection film provided on the light-shielding film, wherein the anti-reflection film includes the same etching characteristics or the same as the light-shielding film Etching selective materials. The phase shift blank mask as described in item 1 of the patent application range, wherein the stacked portion between the phase shift film and the light shielding film has a surface reflectance of 10% to 40%. The phase shift blank mask as described in item 1 of the scope of the patent application further includes a hard mask film provided on the light shielding film and the phase shift film that are sequentially stacked. The phase shift blank mask as described in item 16 of the patent application range, wherein the hard mask film includes a material having the same etching characteristics as the phase shift film and having the same etching selectivity as the light shielding film. The phase shift blank mask as described in item 16 of the patent application scope, wherein the hard mask film includes one of the following: silicon (Si); and silicon (Si) compounds, wherein the silicon (Si) compound is other than silicon In addition to (Si), it also contains one or more light elements. The silicon (Si) compounds include SiN, SiC, SiO, SiCN, SiCO, SiNO, SiCON, SiB, SiBN, SiBC, SiBO, SiBCN, SiBCO, SiBNO and SiBCON; molybdenum silicide (MoSi); and molybdenum silicide (MoSi) compounds including MoSiN, MoSiC, MoSiO, MoSiCN, MoSiCO, MoSiNO, and MoSiCON. The phase shift blank mask as described in item 16 of the patent application range, wherein the etching rate of the hard mask film is 10Å/sec or less. The phase-shift blank mask as described in item 16 of the patent application range, wherein the thickness of the hard mask film is 20Å to 200Å. The phase shift blank mask as described in item 1 of the scope of the patent application, which further includes a resist film provided on the light-shielding film and a charge dissipation layer provided on the resist film. The phase shift blank mask as described in item 21 of the patent application range, wherein the charge dissipation layer includes a self-doped water-soluble conductive polymer. The phase shift blank mask as described in Item 21 of the patent application range, wherein the thickness of the charge dissipation layer is 5 nm to 60 nm. The phase-shift blank mask as described in Item 16 of the scope of the patent application further includes an anti-reflection film provided on the light-shielding film. A phase shift reticle manufactured by using the phase shift blank mask according to any one of claims 1 to 24.

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