TW202006462A - Blankmask and photomask - Google Patents

Abstract

A blankmask according to the present disclosure includes a light-shielding film provided on a transparent substrate; and a hard mask film provided on the light-shielding film and comprising molybdenum chromium (MoCr). Thus, the hard mask film has not only an enhanced etching speed but also sufficient etching resistance to fluorine (F)-based dry etching, so that an etching load against a resist film can be decreased and a hard mask film pattern and a light-shielding film pattern can be improved in a line edge roughness (LER), thereby forming a photomask for high-precision pattern printing.

Description

Blank mask and photomask, and method for manufacturing the same

[ Cross-reference of related applications ] This application claims Korean Patent Application No. 10-2018-0081353 filed with the Korean Intellectual Property Office on July 13, 2018 and filed with the Korean Intellectual Property Office on August 13, 2018 The rights and interests of Korean Patent Application No. 10-2018-0094127, the disclosure content of which is incorporated herein by reference in its entirety.

The present invention relates to a blank mask, and in particular to a blank mask and a photomask and a method of manufacturing the same, and more specifically, to a blank mask and a light A mask and a method of manufacturing the same, in which a hard mask film is provided for manufacturing semiconductor devices in the category of 32 nm or less (specifically, 14 nm or less).

Today, high-level semiconductor microfabrication technology has become very important to meet the demand for miniaturization of circuit patterns due to the high integration of large integrated circuits. In the case of a highly integrated circuit, the circuit layout or the like due to integration, the contact hall pattern for interlayer connection (contact hall pattern) and the miniaturization of circuit wiring for high-speed operation and low power consumption Demand has increased. In order to meet these demands, techniques for recording high-resolution patterns along with precise circuit patterns have been required when manufacturing photomasks in which initial circuit patterns are recorded.

As part of efforts to realize high-resolution patterns, blank masks with hard masks have recently been developed and applied. Unlike conventional binary blank masks or phase-shift blank masks, this blank mask with a hard mask film contains a hard mask film located at the lower side adjacent to the resist film, and therefore no resist film is used Instead, a hard mask film pattern is used as an etching mask for forming the lower light-shielding film pattern.

In a blank mask using a hard mask film, the hard mask film is so thin that the resist film can be thinner, thereby ultimately achieving high resolution. In addition, compared with the light-shielding film pattern, the etching time required for the hard mask film to form a pattern is relatively short, so that the loading effect can be reduced when forming the pattern, thereby ultimately improving the critical dimension (CD) linearity (Linearity).

Recently, the high resolution of photomasks and the accuracy of pattern printing have become important. The accuracy of this pattern printing is affected by line edge roughness (LER) at the edges of the pattern formed in the reticle, and further affects uniform optical proximity correction (OPC), and therefore The importance of accuracy has gradually increased.

The same applies to the development of technology nodes in particular (for example, from logic 14nm technology to logic 10nm, logic 7nm or below High-tech (high-tech) development) An increasingly important blank mask with a hard mask.

At the same time, the LER of the final pattern depends on various conditions, such as exposure conditions, resists, thin film materials, etching conditions, etc. Specifically, the material of the final pattern and the LER of the upper etching mask used to form the final pattern have a greater influence on the LER of the final pattern.

For a conventional binary blank mask with a hard mask film, the chrome (Cr) group hard mask material is applied to a molybdenum silicide (MoSi) group light-shielding film. In this case, the chromium (Cr) hard mask material is etched through a chlorine (Cl)-based etching gas, and the chromium (Cr) hard mask material has a disadvantage of a slow etching speed. In addition, the chromium (Cr) group hard cover film material has the disadvantage that the etching rate becomes slower when the oxygen (O) content is reduced to improve the pattern shape of the resist film. This problem ultimately makes the LER of the chromium (Cr) group hard mask pattern poor, and also causes the LER of the light shielding film formed using the hard mask film pattern as an etch mask. In particular, this does not matter in the low-end tech (low-end tech), but in the high-end tech (high-end tech), for example, the process is carried out toward 7nm, 5nm, etc., pattern-based The problem of reduced accuracy of LER's printing rate.

Therefore, an aspect of the present invention is to improve the line edge roughness (LER) of a hard mask film pattern of a binary blank mask with a hard mask, thereby finally providing a blank mask and a photomask and a method of manufacturing the same , Where the LER of the shading film pattern is excellent.

An aspect of the present invention is to provide a blank mask and a photomask and a method of manufacturing the same, in which the pattern is implemented in the category of 32 nm or less (specifically, 14 nm or less).

According to an embodiment of the present invention, a blank mask may be provided, the blank mask including: a light-shielding film provided on a transparent substrate; and a hard cover film provided on the light-shielding film and containing chromium (Cr) and one or Many kinds of metals.

The metal may contain one or more types of metals selected from the group consisting of molybdenum (Mo), titanium (Ti), titanium (zirconium; Zr), vanadium (V), and manganese (Mn) , Iron (Fe), cobalt (cobalt; Co), nickel (nickel; Ni), copper (copper; Cu), zinc (zinc; Zn), gallium (gallium; Ga), germanium (germanium; Ge), Niobium (Nb), Ruthenium (Ru), Rhodium (Rhodium; Rh), Palladium (Palladium; Pd), Silver (silver; Ag), Cadmium (Cd), Indium (Indium), Tin (Tin; Sn), hafnium (hafnium; Hf), tantalum (tantalum; Ta), tungsten (tungsten; W), osmium (osmium; Os), iridium (iridium; Ir), platinum (platinum; Pt), gold ( gold; Au), aluminum (Al), magnesium (magnesium; Mg), lithium (lithium; Li), and selenium (selenium; Se).

The hard mask may contain only metal and chromium (Cr), or may contain one or more of oxygen (O), carbon (carbon; C), and nitrogen (N) in addition to metal and chromium (Cr) Kind of light elements.

The hard cover film may contain only molybdenum chromium (MoCr), or may contain one or more types of light weight among oxygen (O), carbon (C) and nitrogen (N) in addition to molybdenum chromium (MoCr) element.

A molybdenum chromium target (molybdenum chromium target) may be used to form a hard cover film, and the composition ratio of the target is Mo:Cr=0.1 atomic percent (at%): 99.9 atomic percent to 30 atomic percent: 70 atomic percent.

The content of the metal contained in the hard mask film may be 0.1 atomic percent to 30 atomic percent.

The hard mask film may contain metal and chromium (Cr), and the composition ratio (M/Cr) between the metal and chromium (Cr) is in the range of 1/1000 to 1/5.

In addition to molybdenum silicide (MoSi), the light-shielding film may contain at least one kind of material among oxygen (O), carbon (C), and nitrogen (N).

In summary, the embodiments of the present invention will be described in more detail below with reference to the drawings. However, the examples are provided for illustrative purposes only and should not be construed as limiting the scope of the invention. Therefore, those of ordinary skill in the art will understand that various modifications and equivalents can be made according to the embodiments. In addition, the scope of the present invention must be defined in the appended claims.

FIG. 1 is a cross-sectional view of a blank mask according to an embodiment of the present invention.

Referring to FIG. 1, a blank mask 100 according to the present invention includes a light-shielding film 108, a hard mask film 110, and a resist film 112 that are sequentially formed on a transparent substrate 102.

The transparent substrate 102 has a size of 6 inches×6 inches×0.25 inches (width×length×thickness), and a transmittance of 90% or more with respect to exposure light having a wavelength of 200 nm or less.

The light shielding film 108 and the hard mask film 110 can be formed by using various methods of physical deposition or chemical deposition, for example, by chemical vapor deposition (CVD), direct current (DC) sputtering, DC magnetron sputtering (magnetron sputtering), radio frequency (radio frequency; RF) sputtering and ion beam sputtering are selected from any one of them. In addition, the sputtering method may use a single target or multiple simultaneously mounted targets to grow the film.

The light shielding film 108 may have a single layer structure or a multiple layer structure having two or more layers. In the case of a double-layer structure, the light-shielding film 108 can be divided into a light-shielding layer 104 and an anti-reflection layer 106.

The light-shielding film 108 may be made of a metal silicide compound containing silicon and one or more kinds of metals selected from the group consisting of titanium (Ti), vanadium (V), and chromium ( Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), zinc (Zn), gallium (Ga), germanium (Ge), zirconium (Zr), niobium ( Nb), Molybdenum (Mo), Ruthenium (Ru), Rhodium (Rh), Palladium (Pd), Silver (Ag), Cadmium (Cd), Indium (In), Tin (Sn), Hafnium (Hf), Tantalum ( Ta), tungsten (W), osmium (Os), iridium (Ir), platinum (Pt), gold (Au), aluminum (Al), magnesium (Mg), lithium (Li) and selenium (Se), or may be The aforementioned metal silicide compound added with at least one kind of material among oxygen (O), carbon (C), and nitrogen (N) is made.

Preferably, the light-shielding film 108 may be made of a molybdenum silicide (MoSi) compound, and contains at least nitrogen (N). For example, the light-shielding layer 104 may be made of molybdenum silicide nitride (MoSiN), and the anti-reflection layer 106 may be made of molybdenum silicide nitride (MoSiN), molybdenum silicide oxide nitride (MoSiON), or Etc. made.

The light-shielding film 108 may have a thickness of 30 nm to 70 nm, and preferably has a thickness of 35 nm to 60 nm. The light-shielding film 108 is a member in which a final pattern is formed, and needs to have a predetermined optical density. Therefore, it is difficult to satisfy the optical density when the thickness of the light-shielding film 108 is less than or equal to 30 nanometers, and when the thickness of the light-shielding film 108 is greater than 70 nanometers, there is a 3D effect (width × length × thickness; pattern printing error caused by the thickness) )The problem.

The light-shielding film 108 has an optical density of 2.5 to 3.5 with respect to exposure light of 193 nanometers, and the uniformity of the optical density is distributed within 0.1 over an area of 142 square millimeters.

When the stress is defined by TIR, the TIR change rate of the light-shielding film 108 is 200 nm or less compared to the transparent substrate 102, and preferably 100 nm or less.

After the film is grown, the light-shielding film 108 may be additionally subjected to ion plating, ion beam, or the like under vacuum or in a gas atmosphere using one or more kinds selected from reactive oxidizing gas and nitrating gas. Plasma (plasma) surface treatment, rapid thermal process (rapid thermal process; RTP), vacuum hot plate baking (vacuum hot plate bake) device and furnace (furnace) process.

When the blank mask 100 is used to manufacture a photomask, the hard mask film 110 serves as an etching mask of the light-shielding film 108 to be disposed thereunder. For this purpose, the dry etching selectivity of the hard mask film 110 to the light-shielding film 108 is 10 or higher, and preferably 30 or higher, and the thickness is 2 nm to 20 nm , And preferably 3 nm to 10 nm.

The hard cover film 110 may be made of metal chromium (M) containing chromium (Cr) and one or more kinds of metals selected from the following: titanium (Ti), vanadium (V), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), zinc (Zn), gallium (Ga), germanium (Ge), zirconium (Zr), niobium (Nb), molybdenum (Mo), Ruthenium (Ru), Rhodium (Rh), Palladium (Pd), Silver (Ag), Cadmium (Cd), Indium (In), Tin (Sn), Hafnium (Hf), Tantalum (Ta), Tungsten (W), osmium (Os), iridium (Ir), platinum (Pt), gold (Au), aluminum (Al), magnesium (Mg), lithium (Li) and selenium (Se), or may be added with oxygen At least one kind of material (O), carbon (C), and nitrogen (N) is made of metal chromium.

Preferably, the hard cover film 110 may be made of molybdenum chromium (CrMo) or molybdenum chromium (CrMo) compounds, such as MoCrN, MoCrO, MoCrC, MoCrCN, MoCrCO, MoCrON, MoCrCON, and the like.

When the composition ratio between molybdenum (Mo) and chromium (Cr) contained in the hard cover film 110 is represented by "Mo/Cr", the range of the composition ratio may preferably be 1/1000 to 1/5.

Based on the composition ratio, the content of molybdenum (Mo) contained in the hard cover film 110 may be 0.1 atomic percent (at%) to 30 atomic percent, and preferably 5 atomic percent to 20 atomic percent. When the content of molybdenum (Mo) is less than 0.1 atomic percent, the content of molybdenum (Mo) is so low that it is difficult to increase the etching rate, so that the final improvement of the LER of the pattern is not good. On the other hand, when the content of molybdenum (Mo) is higher than 30 atomic percent, there is a problem of having cleaning resistance and reducing etching selectivity when etching the lower light-shielding film.

The hard cover film 110 may be formed using a single target of molybdenum chromium (MoCr) or multiple targets containing molybdenum (Mo) and chromium (Cr). The composition ratio of a single target may be Mo:Cr=0.1 atomic percent: 99.9 atomic percent to 30 atomic percent: 70 atomic percent.

The hard cover film 110 may be designed to have a single-layer structure, or two or more layers or a continuous layer structure in which the content of molybdenum (Mo) is adjusted, or may alternatively have two or more layers or A continuous layer structure in which the composition of one or more kinds of materials among oxygen (O), carbon (C), and nitrogen (N) changes.

During the manufacturing process of the photomask, the hard mask film 110 may be selectively removed after the light-shielding film pattern is completely formed.

The resist film 112 is formed by applying spin coating to a chemically amplified resist (CAR), and the thickness of the resist film is 40 nm to 150 nm. ( Example )

Examples : Manufacturing blank masks and photomasks

This example discloses the use of a hard mask film made of a MoCr compound to make a binary blank mask and photomask.

First, referring to FIG. 1, the transparent substrate 102 is prepared to be controlled to have a size of 6 inches×6 inches×0.25 inches (width×length×thickness), a flatness (TIR) of 300 nm or less, and 2nm/6.35mm birefringence.

Next, the light-shielding layer 104 made of MoSiN is formed through the following steps: a MoSi [10 atomic percent: 90 atomic percent] compound target is mounted on the DC magnetron sputtering device, and Ar:N ₂ =7 standard milliliters/minute (sccm ): 3 standard milliliters/minute of processing gas, and supply of 0.7 kilowatts (kW) of processing power. Next, the anti-reflection layer 106 made of MOSiN is formed by injecting a processing gas of Ar:N ₂ =7.0 standard ml/min: 6.5 standard ml/min and supplying a processing power of 0.6 kW, thereby finally completing the manufacture of the light-shielding film 108 . Here, as a result of measuring the optical density and the reflectance of the light-shielding film 108 with respect to exposure light having a wavelength of 193 nm, the light-shielding film 108 exhibits an optical density of 2.95 and a reflectivity of 33.5%. In addition, as a result of measuring the thickness using the XRR device, the light-shielding film 108 exhibits a thickness of 47.5 nm.

Next, the light-shielding film 108 was heat-treated at a temperature of 350° C. for 20 minutes via a vacuum RTP.

Subsequently, the MoCr hard mask film 110 was grown to a thickness of 4 nanometers through the following steps: using a MoCr [5 atomic percent: 95 atomic percent] target on the light shielding film 108, injecting 8 standard milliliters/minute of Ar processing gas, and supplying 0.7 Kilowatt processing power.

Next, the hard mask film 110 is spin-coated using a chemically amplified resist film 112 with a thickness of 100 nm, so that the binary blank mask 100 is completely manufactured.

The blank mask 100 formed as above is exposed and developed to form a resist film pattern, and the hard mask film is etched with chlorine (Cl)-based gas while using the resist film pattern as an etching mask, thereby forming Hard mask pattern. At this time, the end point detection (EPD) device measured the etching rate of the hard mask film to be 1.2 angstroms per second (Å/sec), and applied 100% over-etching to complete the growth of the hard mask film pattern (over etching).

The resist film pattern is removed, and then the lower light-shielding film is etched with fluorine (F)-based gas while using the hard mask film pattern as an etching mask. At this time, the etching speed of the light-shielding film was measured to be 15.3 Angstroms/sec, and 60% of over-etching was applied in completing the growth of the light-shielding film pattern.

Next, the hard mask pattern is removed, so that the photomask is finally and completely manufactured.

Comparative example: manufacturing blank masks and photomasks

In a comparative example different from the foregoing embodiment, a chromium (Cr) thin film is formed as a hard mask material.

In the blank mask according to the comparative example, a light-shielding film made of MoSiN is formed similarly to the previous embodiment, and the chromium (Cr) hard mask film is grown to a thickness of 4 nm by the following steps: using a chromium (Cr) target Inject 8 standard milliliters/minute of Ar gas as the processing gas, and supply 0.7 kW of processing power.

Next, the chemically amplified resist is spin-coated to a thickness of 100 nm, thereby finally completing the blank mask.

The blank mask 100 formed as above is exposed and developed to form a resist film pattern, and the hard mask film is etched with a chlorine (Cl)-based gas while using the resist film pattern as an etching mask to form a hard mask Film pattern. At this time, the EPD device measured the etching rate of the hard mask film to be 0.7 angstroms/second.

Next, similar to the previous embodiment, the lower light shielding film is etched using the hard mask film pattern, and then the hard mask film pattern is removed to completely manufacture the photomask.

LER measuring -I : Shading film pattern

LER measurement was performed on the patterns formed according to the foregoing examples and comparative examples. LER measurement was performed on 7 X 7 points on the hard mask film pattern and the light-shielding film pattern. However, it is difficult to actually measure the hard mask film pattern, and therefore the light-shielding film.

As a result of LER measurement, the LER of the light-shielding film pattern formed according to the example was 2.1 nm, and the LER of the light-shielding film pattern formed according to the comparative example was 3.8 nm. Therefore, compared with the comparative example, the LER of the light-shielding film pattern using the MoCr hard mask material according to the embodiment is improved by about 60% or more.

LER measuring -II : Hard mask pattern

In consideration of the difficulty of measuring the aforementioned LER measurement-I of the LER of the hard mask film pattern, the hard mask films according to Examples and Comparative Examples were grown to a thickness of 30 nm, and then a patterning process and LER measurement were performed.

As a result of LER measurement, the LER of the hard mask film pattern formed according to the example is 2.5 nm, and the LER of the hard mask film pattern formed according to the comparative example is 4.5 nm. Therefore, compared with the comparative example, the LER of the MoCr hard mask film according to the example is improved by about 50% or more.

Etching speed evaluation based on the composition of the hard mask

In order to evaluate the etching rate of the hard mask film according to the present invention, hard mask films of different compositions were grown and then tested.

[Table 1]

Referring to Table 1, by increasing the content of molybdenum (Mo) contained in the MoCr target, the content of molybdenum (Mo) in the hard mask films according to Example #1 to Example #3 is increased. In the results, it should be understood that the etching rate increases as the molybdenum (Mo) content increases.

On the other hand, the comparative example uses only chromium (Cr) when growing the hard mask film and exhibits an etching rate of 0.7 Angstroms/second, which is slower than those of the hard mask film made of molybdenum chromium (MoCr).

As described above, the hard mask film made of only molybdenum chromium (MoCr) or molybdenum chromium (MoCr) compound according to the present invention not only has an improved etching speed, but also has sufficient corrosion resistance to fluorine (F) based dry etching Etchability, so that the etching load on the resist can be reduced and the LER of the hard mask film pattern and the light-shielding film pattern can be improved, thereby forming a photomask for high-precision pattern printing.

In the blank mask with a hard mask according to the present invention, only molybdenum chromium (MoCr) or molybdenum chromium (MoCr) compound is provided as a hard mask film material.

Thereby, the LER of the hard mask film pattern according to the present invention is improved to finally increase the LER of the light-shielding film pattern, thereby ensuring high-precision pattern printing when using the manufactured photomask for wafer printing.

In addition, according to the present invention, the pattern may be formed in the category of 32 nm or less (specifically, 14 nm or less).

Although the present invention has been illustrated and described with reference to exemplary embodiments, the technical scope of the present invention 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 according to these exemplary embodiments. In addition, as defined in the appended claims, it will be apparent that such changes and modifications relate to the technical scope of the present invention.

100‧‧‧Blank mask 102‧‧‧Transparent substrate 104‧‧‧Light shielding layer 106‧‧‧Anti-reflective layer 108‧‧‧Light shielding film 110‧‧‧Hard cover film 112‧‧‧ Resist film

The above and/or other aspects will become apparent and easier to understand from the following description of exemplary embodiments in conjunction with the accompanying drawings, wherein: FIG. 1 is a cross-sectional view of a blank mask according to an embodiment of the present invention.

100‧‧‧ Blank mask

102‧‧‧Transparent substrate

104‧‧‧ shading layer

106‧‧‧Anti-reflection layer

108‧‧‧shading film

110‧‧‧ Hard cover film

112‧‧‧resist film

Claims (11)

A blank mask includes: a transparent substrate; a shading film provided on the transparent substrate; and a hard mask film provided on the shading film and including chromium (Cr) and one or more kinds of metals. The blank mask as described in item 1 of the patent application scope, wherein the metal includes one or more types of metals selected from the group consisting of molybdenum (Mo), titanium (Ti), zirconium (Zr), and vanadium (V ), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), zinc (Zn), gallium (Ga), germanium (Ge), niobium (Nb), ruthenium (Ru) ), rhodium (Rh), palladium (Pd), silver (Ag), cadmium (Cd), indium (In), tin (Sn), hafnium (Hf), tantalum (Ta), tungsten (W), osmium (Os) ), iridium (Ir), platinum (Pt), gold (Au), aluminum (Al), magnesium (Mg), lithium (Li) and selenium (Se). The blank mask as described in item 1 of the patent application scope, wherein the hard mask film includes only the metal and chromium (Cr), or in addition to the metal and chromium (Cr), oxygen (O), One or more kinds of light elements among carbon (C) and nitrogen (N). The blank mask as described in item 1 of the patent application scope, wherein the hard mask film only includes molybdenum chromium (MoCr), or in addition to molybdenum chromium (MoCr), it also includes oxygen (O), carbon (C) and nitrogen (N) One or more kinds of light elements. The blank mask as described in item 4 of the patent application scope, in which the hard mask film is formed using a molybdenum-chromium (MoCr) target, and the composition ratio of the target is Mo:Cr=0.1 atomic percent: 99.9 atomic percent~30 Atomic percentage: 70 atomic percentage. The blank mask as described in item 1 of the patent application scope, wherein the thickness of the hard mask film is 2 nm to 20 nm. The blank mask as described in item 1 of the patent application scope, wherein the content of the metal contained in the hard mask film is 0.1 atomic percent to 30 atomic percent. The blank mask as described in item 1 of the patent application scope, wherein the hard mask film includes the metal and chromium (Cr), and the composition ratio (M/Cr) between the metal and chromium (Cr) is 1 /1000 to 1/5. The blank mask as described in item 1 of the patent application scope, wherein the hard mask film comprises a single-layer structure, a continuous layer structure in which the composition or composition ratio is changed, or two or more of which the composition or composition ratio changes between Multi-layer structure of two layers. The blank mask as described in item 1 of the patent application scope, wherein the light-shielding film includes at least one kind of material among oxygen (O), carbon (C), and nitrogen (N) in addition to molybdenum silicide (MoSi) . A photomask manufactured by the blank mask according to any one of the items 1 to 10 of the patent application scope.

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