Blank mask and photomask

Abstract

A blank mask according to an embodiment includes: a substrate; and a conductive layer disposed on the substrate, in which the conductive layer includes a first layer and a second layer having different conductivity, and the conductivity of the conductive layer is 500 S / cm to 2000 S / cm.

Description

Technical Field

[0001] Embodiments relate to a blank mask and a photomask. Background Art

[0002] A semiconductor integrated circuit (Large Scale Integration: LSI) device or a flat panel display (Flat Panel Display: FPD) device is manufactured through a photolithography process in which a pattern is transferred using a photomask.

[0003] The blank mask has a structure in which a metal film or a metal compound film including a metal material and a photoresist film are formed on a transparent substrate including synthetic quartz glass. The photomask includes a metal pattern or a metal compound pattern formed by patterning a thin film of the blank mask.

[0004] The thin film includes a light shielding film, an anti-reflection film, a phase-shift film, a semi-transmissive film or a reflective film according to the required optical characteristics. The blank mask includes at least one or more of the thin films, which are patterned into a desired shape to manufacture a photomask including a transfer pattern.

[0005] On the other hand, the photomask transfers the pattern through a contact or non-contact photolithography process, thereby forming a structure constituting a device on the substrate to be transferred.

[0006] At this time, as the number of times the photomask is repeatedly used in the photolithography process increases, the electrostatic charge charged to the photomask accumulates, and when the charge difference between the patterns exceeds the breakdown voltage, static electricity is generated between the patterns, damaging the patterns of the photomask. In particular, the more separated the pattern, the higher the potential difference with the adjacent pattern, and therefore more damage occurs due to the electrostatic discharge current. In particular, the separated pattern has a higher potential difference with the adjacent pattern, and therefore is more easily damaged by the electrostatic discharge current. This causes the problem that the photomask with the damaged pattern must be modified or discarded.

[0007] Therefore, a new structure of a photomask capable of reducing the electrostatic discharge current of the photomask as described above is required. Summary of the invention

[0008] Technical issues

[0009] The embodiment provides a photomask capable of reducing a discharge current generated by static electricity of a pattern and improving a discharge voltage.

[0010] Technical Solution

[0011] A blank mask according to an embodiment includes: a substrate; and a conductive layer disposed on the substrate, the conductive layer including a first layer and a second layer having different conductivities, and the conductivity of the conductive layer is 500 S / cm to 2000 S / cm.

[0012] Beneficial Effects

[0013] The blank mask according to the embodiment includes a conductive layer having a set range of conductivity. Therefore, a photomask manufactured from the blank mask is formed into a pattern having a set range of conductivity.

[0014] Therefore, the discharge voltage of the pattern of the photomask increases. In addition, when static electricity is generated between adjacent patterns, the intensity of the discharge current caused by the static electricity decreases. Therefore, the magnitude of the heat temperature generated by the discharge current decreases. Therefore, the pattern of the photomask can be prevented from being damaged by the heat generated by the discharge current between adjacent patterns.

[0015] That is, the conductivity of the conductive layer of the blank mask used to manufacture the photomask is reduced, and the conductivity of the pattern of the photomask manufactured from the blank mask is also reduced.

[0016] Therefore, the current density of the discharge current, which is proportional to the size of the conductivity and the size of the electric field, decreases. Therefore, when static electricity is generated between adjacent patterns, the size of the discharge current generated by the static electricity decreases. Therefore, the size of the heating temperature generated by the discharge current decreases.

[0017] Therefore, the blank mask according to the embodiment can manufacture a photomask with improved reliability. In addition, the photomask according to the embodiment can form a circuit pattern with a uniform and fine line width on a wafer by preventing damage to the pattern, and can increase the life of the photomask. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 is a cross-sectional view of a blank mask according to an embodiment.

[0019] Figure 2 It is shown Figure 1 Magnified view of area A.

[0020] Figure 3 is a diagram illustrating a cross-sectional view of a photomask according to an embodiment.

[0021] Figure 4 1 is a diagram for explaining the principle of static electricity generation in the photomask according to the embodiment.

[0022] Figure 5 and Figure 6 FIG. 1 is a diagram for explaining changes in conductivity of a pattern of a photomask according to an embodiment and current density according to an electric field (E-field).

[0023] Figure 7 : is a graph showing a discharge voltage and a discharge current depending on the conductivity of the patterns of the photomasks according to the embodiment and the comparative example.

[0024] Figure 8 are photographs showing damage of patterns of photomasks according to the embodiment and the comparative example. DETAILED DESCRIPTION

[0025] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. However, the spirit and scope of the present disclosure are not limited to a part of the described embodiments, and can be implemented in various other forms, and within the spirit and scope of the present disclosure, one or more elements of the embodiments can be selectively combined and rearranged. In addition, unless explicitly defined and described otherwise, the terms (including technical terms and scientific terms) used in the embodiments of the present disclosure can be interpreted as having the same meaning as the meanings commonly understood by those of ordinary skill in the art to which the present disclosure belongs, and the terms (such as terms defined in commonly used dictionaries) can be interpreted as having the same meanings as their meanings in the context of the relevant technology. In addition, the terms used in the embodiments of the present disclosure are used to describe the embodiments and are not intended to limit the present disclosure.

[0026] In this specification, unless otherwise specified in a phrase, a singular form may also include a plural form, and when described as "at least one (or more) of A (and), B and C" may include at least one of all combinations that can combine A, B and C.

[0027] In addition, when describing the elements of the embodiments of the present disclosure, terms such as first, second, A, B, (a), and (b) may be used. These terms are only used to distinguish an element from other elements, and the terms are not limited to the nature, order, or sequence of the elements.

[0028] In addition, when an element is described as being “connected,” “coupled” or “contacting” another element, it may include not only the case where the element is directly “connected,” “coupled” or “contacting” the other element, but also the case where the element is “connected,” “coupled” or “contacting” with another element between the element and the other element.

[0029] In addition, when described as being formed or arranged "on" or "under" each element, "on" or "under" may include not only the case where two elements are directly connected to each other, but also the case where one or more other elements are formed or arranged between the two elements.

[0030] In addition, when expressed as “on (above)” or “under (below)”, it may include not only an upper direction based on one element but also a lower direction based on one element.

[0031] Hereinafter, a photomask according to an embodiment will be described with reference to the accompanying drawings.

[0032] Figure 1 is a cross-sectional view of a blank mask according to an embodiment.

[0033] Reference Figure 1 , a blank mask 1000 according to an embodiment includes a substrate 100 and a conductive layer 200 .

[0034] The substrate 100 includes a transparent substrate. For example, the substrate 100 may be quartz glass, soda lime, a glass substrate, an alkali-free glass substrate, or a low thermal expansion glass substrate. For example, the substrate 100 includes a quartz substrate.

[0035] The conductive layer 200 is disposed on the entire surface of the substrate 100. The conductive layer 200 has a conductivity within a set range. Therefore, the pattern of the photomask manufactured from the blank mask also has a conductivity within a set range. Therefore, damage to the pattern of the photomask manufactured from the blank mask can be prevented.

[0036] The conductive layer 200 includes a metal. In detail, the conductive layer 200 includes a metal oxide. In detail, the conductive layer 200 includes a chromium oxide. More specifically, the conductive layer 200 includes a chromium oxide containing at least one of chromium, carbon, oxygen, and nitrogen. More specifically, the conductive layer 200 includes a chromium oxide containing at least one of CrO, CrON, CrCO, and CrCON.

[0037] Reference Figure 2 , the conductive layer 200 includes a plurality of layers. For example, the conductive layer 200 includes a first layer 210 and a second layer 220. In detail, the second layer 220 is disposed on at least one of the upper surface and the lower surface of the first layer 210.

[0038] although Figure 2 It is shown that the conductive layer 200 is formed in three layers, but the embodiment is not limited thereto. The conductive layer 200 is formed in two layers or four or more layers.

[0039] The first layer 210 and the second layer 220 have different compositions. In addition, the first layer 210 and the second layer 220 have different composition ratios. In addition, the first layer 210 and the second layer 220 have different physical properties.

[0040] For example, the first layer 210 includes chromium, carbon, and oxygen. In addition, the second layer 220 includes chromium, carbon, oxygen, and nitrogen.

[0041] In addition, the first layer 210 and the second layer 220 have different oxygen contents. That is, the composition ratio of oxygen in the metal oxide of the first layer 210 and the composition ratio of oxygen in the metal oxynitride of the second layer 220 are different.

[0042] The conductivity of the conductive layer 200 is controlled by controlling the oxygen content of the first layer 210 and the second layer 220 .

[0043] In addition, the first layer 210 and the second layer 220 have different electrical conductivities. For example, the electrical conductivity of the first layer 210 is greater than the electrical conductivity of the second layer 220. Alternatively, the electrical conductivity of the second layer 220 is greater than the electrical conductivity of the first layer 210.

[0044] In addition, the first layer 210 and the second layer 220 have different thicknesses. In detail, the thickness of the first layer 210 is greater than the thickness of the second layer 220.

[0045] When the blank mask is patterned to form a photomask, the first layer 210 is defined as a light shielding layer of the photomask. In addition, the second layer 220 is defined as an anti-reflection layer of the photomask.

[0046] Figure 3 is a diagram illustrating a cross-sectional view of a photomask according to an embodiment.

[0047] The photomask 2000 applies photoresist to the blank mask 1000 and performs exposure and development using an electron beam. That is, the exposure and development process is performed using an electron beam according to the required semiconductor circuit information. Then, after etching chrome, the photoresist is removed.

[0048] Therefore, the photomask forms a plurality of patterns P having semiconductor circuit information. For example, the photomask 2000 includes a plurality of patterns having set line widths and intervals. In detail, the photomask 2000 includes a plurality of patterns P having line widths greater than 0um to less than 20um and intervals greater than 0um to less than 20um.

[0049] That is, the photomask 2000 blocks light in the region where the pattern P is formed, and transmits light in the substrate 100 where no pattern is formed. Therefore, the photomask is disposed on a wafer, and a circuit pattern of semiconductor circuit information included in the photomask can be formed on the surface of the wafer through exposure, development, and etching processes.

[0050] On the other hand, a plurality of patterns P of the photomask are arranged adjacent to each other with a thin line width. Therefore, a discharge current may flow between adjacent patterns due to static electricity generated in the patterns. Such a discharge current causes heat, and damage to the patterns occurs due to such heat temperature.

[0051] Figure 41 is a diagram for explaining the principle of static electricity generation in the photomask according to the embodiment.

[0052] Reference Figure 4 , a plurality of patterns are disposed on the substrate 100. For example, a first pattern P1 and a second pattern P2 having circuit information and adjacent to each other are disposed on the substrate 100.

[0053] In the photomask, electrostatic charges are accumulated in each pattern P1 and P2 during the manufacturing process or the processing. As a result, free electrons according to the electrostatic charges are emitted from the first pattern P1 or the second pattern P2. At this time, when the air between the patterns reaches the dielectric breakdown strength, the air between the patterns becomes a conductor and becomes a conductive path. Therefore, the free electrons emitted from the first pattern P1 or the second pattern P2 move. For example, the free electrons emitted from the first pattern P1 move along the conductive path to the second pattern P2. As a result, a conductive path is formed between the first pattern P1 and the second pattern P2, and current flows along the conductive path. This phenomenon is defined as the discharge of the pattern, and the current flowing along the path is defined as the discharge current. In addition, the voltage generated by the static electricity of the discharge current is defined as the discharge voltage.

[0054] The discharge current causes heat. The heat temperature is proportional to the discharge current. Therefore, as the magnitude of the discharge current increases, the heat temperature also increases. That is, as the discharge current between the first pattern P1 and the second pattern P2 increases, the heat temperature between the first pattern P1 and the second pattern P2 also increases. Therefore, as the heat temperature increases, the first pattern P1 and the second pattern P2 may be damaged.

[0055] Therefore, the pattern of the photomask is damaged. Therefore, when a circuit pattern is formed on a wafer using the photomask, an accurate circuit pattern cannot be formed on the wafer. In addition, when the circuit pattern is formed on the wafer, the line width of the circuit pattern may become uneven.

[0056] The discharge current generated between the first pattern P1 and the second pattern P2 is proportional to the current density (J) of the first pattern P1 and the second pattern P2. In addition, the current density (J) is proportional to the conductivity (σ) and the electric field (E-field, E). In detail, the current density (J) is defined by the following formula.

[0057] [formula]

[0058] Current density (J) = conductivity (σ) * electric field (E-field, E)

[0059] Therefore, in order to reduce the discharge current occurring between the first pattern P1 and the second pattern P2, the current density (J) must be reduced. In addition, in order to reduce the current density (J), the conductivity or the magnitude of the electric field must be reduced.

[0060] On the other hand, the magnitude of conductivity does not affect the electric field.

[0061] Figure 5 and Figure 6 It is a diagram for explaining the change of electric field and the change of current density when the conductivity is different. Figure 5 and Figure 6 : is a graph showing changes in electric field and current density in Experimental Examples 1 and 2 having different conductivities. Experimental Example 1 is a photomask including a pattern having low conductivity, and Experimental Example 2 is a photomask having relatively higher conductivity than Experimental Example 1.

[0062] Reference Figure 5 , the magnitude of the electric field (E-field) in Experimental Examples 1 and 2 has nothing to do with the conductivity. Figure 5 , it can be seen that the magnitudes of the electric fields in Experimental Examples 1 and 2 with different conductivities are almost similar.

[0063] On the other hand, refer to Figure 6 , it can be seen that the current density is related to the conductivity. Figure 6 , it can be seen that the current densities of the patterns P1 and P2 of the experimental example 2 having high conductivity are greater than the current densities of the patterns P1 and P2 of the experimental example 1 having low conductivity.

[0064] Reference Figure 5 and Figure 6 , the size of the conductivity does not affect the size of the electric field, and the conductivity is proportional to the current density. Therefore, if the conductivity of the pattern is reduced, the current density can be reduced. In addition, the size of the discharge current can be reduced by reducing the current density.

[0065] Therefore, the photomask 2000 according to the embodiment controls the conductivity of the pattern to a set range. Therefore, the size of the discharge current generated between adjacent patterns due to the generation of static electricity is reduced. Therefore, the temperature of the heat generated by the discharge current is reduced, thereby reducing damage to the pattern of the photomask.

[0066] On the other hand, the conductivity of the pattern is controlled by controlling the oxygen content of the pattern. In detail, it is formed by controlling the oxygen content of the conductive layer 200 of the blank mask. More specifically, it is formed by controlling the oxygen content of the first layer 210 as a light shielding layer and / or the second layer 220 as an anti-reflection layer. For example, the conductivity range of the conductive layer 200 can be set, and the oxygen content can be increased by an amount that can meet the conductivity range. The magnitude of the conductivity of the first layer 210 and the second layer 220 is inversely proportional to the oxygen content. Therefore, the conductivity of the first layer 210 and the second layer 220 can be reduced by increasing the oxygen content of the first layer 210 and the second layer 220.

[0067] Therefore, the conductivity of the conductive layer 200 of the blank mask 1000 according to the embodiment is 500 S / cm or more. In detail, the conductivity of the conductive layer 200 is 500 S / cm to 2000 S / cm. More specifically, the conductivity of the conductive layer 200 is 1200 S / cm to 1600 S / cm.

[0068] In addition, the conductivity of the pattern P of the photomask 2000 according to the embodiment is 500 S / cm or more. In detail, the conductivity of the pattern P is 500 S / cm to 2000 S / cm. In more detail, the conductivity of the pattern P is 1200 S / cm to 1600 S / cm.

[0069] If the conductivity of the conductive layer 200 and the pattern P is 500 S / cm to 2000 S / cm, the current density of the pattern P is reduced. Therefore, when static electricity is generated in the pattern P, the size of the discharge current generated between the patterns P is reduced. Therefore, when static electricity is generated, damage to the pattern P can be reduced.

[0070] If the conductivity of the conductive layer 200 and the pattern P is less than 500 S / cm, the light shielding properties of the conductive layer 200 and the pattern P are reduced. That is, as the oxygen content of the conductive layer 200 and the pattern P increases, the light transmittance of the conductive layer 200 and the pattern P increases. Therefore, when a circuit pattern is formed on a wafer using a photomask, a uniform line width and a precise circuit pattern cannot be formed. In other words, the properties of the photomask are reduced.

[0071] In addition, if the conductivity of the conductive layer 200 and the pattern P exceeds 2000 S / cm, the current density of the discharge current increases due to the increase in the conductivity of the pattern P. Therefore, when a circuit pattern is formed on a wafer using a photomask, a uniform line width and a precise circuit pattern cannot be formed. In other words, the characteristics of the photomask are degraded.

[0072] In addition, the discharge voltage of the pattern P of the photomask 2000 according to the embodiment is greater than 400 V. In detail, the discharge voltage of the pattern P is 400 V to 550 V. In addition, the discharge current of the pattern P of the photomask 2000 according to the embodiment is greater than 0.5 mA. In detail, the discharge current of the pattern P is 0.5 mA to 2 mA.

[0073] Since the pattern P has the conductivity range as described above, the magnitude of the discharge voltage that generates static electricity in the pattern P increases, and the magnitude of the discharge current decreases. Therefore, since the magnitude of the discharge voltage of the pattern P increases, the generation of static electricity that may occur in the pattern P decreases. In addition, since the magnitude of the discharge current of the pattern P decreases, when static electricity that may occur in the pattern P is generated, damage to the pattern can be reduced.

[0074] Hereinafter, the present invention will be described in more detail by the discharge voltage and discharge current of the conductivity of the pattern of the photomask according to the embodiment and the comparative example. These embodiments are presented only as examples to illustrate the present invention in more detail. Therefore, the present invention is not limited to these examples.

[0075] Example 1

[0076] A quartz substrate is prepared. Next, a conductive layer is formed on the quartz substrate.

[0077] The conductive layer is formed by stacking at least one first layer and at least one second layer on a quartz substrate. The first layer includes chromium oxide containing chromium, oxygen and carbon. In addition, the second layer includes chromium nitride containing chromium, oxygen, carbon and nitrogen.

[0078] Subsequently, the conductivity of the conductive layer was controlled by controlling the oxygen content of the first layer and / or the second layer. As a result, a conductive layer having an (average) conductivity of 1399 S / cm was formed.

[0079] Subsequently, the conductive layer is patterned to produce a photomask.

[0080] Subsequently, a discharge current and a discharge voltage were measured between the patterns of the photomask.

[0081] Example 2

[0082] A conductive layer was formed in the same manner as in Example 1. As a result, a conductive layer having an (average) conductivity of 1274 S / cm was formed.

[0083] Subsequently, the conductive layer is patterned to produce a photomask.

[0084] Subsequently, a discharge current and a discharge voltage were measured between the patterns of the photomask.

[0085] Comparative Example 1

[0086] A conductive layer was formed in the same manner as in Example 1. As a result, a conductive layer having an (average) conductivity of 16700 S / cm was formed.

[0087] Next, the conductive layer is patterned to produce a photomask.

[0088] Next, the discharge current and the discharge voltage were measured between the patterns of the photomask.

[0089] Comparative Example 2

[0090] A conductive layer was formed in the same manner as in Example 1. As a result, a conductive layer having an (average) conductivity of 2690 S / cm was formed.

[0091] Next, the conductive layer is patterned to produce a photomask.

[0092] Next, the discharge current and the discharge voltage were measured between the patterns of the photomask.

[0093] [Table 1]

[0094] Example 1 Example 2 Conductivity (S / cm) 1399 1274 Optical density (450nm) 3.11 3.17 Etching rate(s) 552 546 Etching deviation(nm) 150.08 143.06

[0095] Figure 7 is a graph showing discharge voltage and discharge current according to patterns of the embodiment and the comparative example.

[0096] Reference Figure 7 , the discharge voltages of the patterns according to Example 1 and Example 2 are greater than the discharge voltage of the comparative example. Specifically, the discharge voltage of the pattern according to Example 1 is 500V, the discharge voltage of the pattern according to Example 2 is 450V, the discharge voltage of the pattern according to Comparative Example 1 is 200V, and the discharge voltage of the pattern according to Comparative Example 2 is 250V.

[0097] Therefore, the patterns according to Embodiment 1 and Embodiment 2 have a large work function (which is the minimum energy for generating static electricity), so that discharge occurs at a high voltage. That is, the discharge voltage is large.

[0098] In addition, the discharge currents of the patterns according to Examples 1 and 2 are less than that of the comparative example. Specifically, the discharge current of the pattern according to Example 1 is 0.9 mA, the discharge current of the pattern according to Example 2 is 1.02 mA, the discharge current of the pattern according to Comparative Example 1 is 12.69 mA, and the discharge current of the pattern according to Comparative Example 2 is 2.5 mA.

[0099] That is, the patterns according to Example 1 and Example 2 have small conductivity. Therefore, the patterns according to Example 1 and Example 2 have small current density. Therefore, the size of the discharge current flowing between the patterns is also small.

[0100] Therefore, since the patterns according to Embodiment 1 and Embodiment 2 have a small discharge current, the magnitude of the heat generation temperature generated between the patterns when static electricity is generated is reduced.

[0101] Figure 8 are optical images showing damage to patterns of the photomasks according to the embodiment and the comparative example when static electricity is generated.

[0102] Reference Figure 8 In the photomasks according to Embodiment 1 and Embodiment 2, when static electricity is generated in the pattern, since the magnitude of the discharge current flowing between the patterns is small, deformation of the pattern occurs only in a local area, and the degree of deformation of the pattern is not large.

[0103] On the other hand, in the photomasks according to Comparative Examples 1 and 2, when static electricity is generated in the pattern, since the magnitude of the discharge current flowing between the patterns is large, deformation of the pattern occurs in a large area and the degree of deformation of the pattern is large.

[0104] That is, in the photomasks according to Embodiment 1 and Embodiment 2, the discharge voltage of the pattern having the conductivity in the set range is high, and the discharge current is small. Therefore, when static electricity is generated in the pattern and the discharge current flows between the patterns, the heating temperature caused thereby is reduced. Therefore, the pattern can be prevented from being damaged by the heating temperature generated between the patterns. Therefore, the photomask according to the embodiment has improved reliability and can increase the service life.

[0105] In addition, referring to Table 1, the patterns according to Example 1 and Example 2 have an optical density of 3 or more in the wavelength range of 450 nm. Therefore, the patterns according to Example 1 and Example 2 have improved light shielding characteristics.

[0106] In addition, the pattern according to the embodiment has an etching speed of less than 600 seconds. In addition, the pattern according to the embodiment has an etching deviation of less than 200nm. Here, the etching deviation is defined as the deviation from the line width of the pattern to be set. Therefore, the photomask according to the embodiment includes a pattern with a thin line width and improved etching characteristics.

[0107] Therefore, the photomask according to the embodiment can improve the line width and uniformity of a pattern and reduce the magnitude of a discharge current generated by static electricity between adjacent patterns.

[0108] Therefore, a circuit pattern having a uniform and fine line width may be formed on a wafer through the photomask according to the embodiment, and the lifespan and reliability of the photomask may be improved.

[0109] The features, structures, effects, etc. described in the above embodiments are included in at least one embodiment and are not necessarily limited to one embodiment. In addition, the features, structures, effects, etc. shown in each embodiment can be combined or modified by a person of ordinary skill in the technical field to which the embodiment belongs for other embodiments. Therefore, the contents related to such combinations and modifications should be interpreted as being included in the scope of the embodiments.

[0110] In the above, the embodiment has been mainly described, but this is only an example and does not limit the embodiment, and a person skilled in the art to which the embodiment belongs will understand that various modifications and applications not shown above can be made without departing from the essential features of the present embodiment. For example, the various components specifically shown in the embodiment can be implemented by modification. In addition, the differences related to these modifications and applications should be interpreted as being included in the scope of the embodiment set forth in the appended claims.

Claims

1. A blank mask, comprising: substrate; as well as a conductive layer, the conductive layer being disposed on the substrate, Wherein, the conductive layer comprises a first layer and a second layer having different electrical conductivities, and Wherein, the electrical conductivity of the conductive layer is 500 S / cm to 2000 S / cm.

2. The blank mask according to claim 1, wherein: The electrical conductivity of the conductive layer is 1200 S / cm to 1600 S / cm.

3. The blank mask according to claim 1, wherein: The first layer includes a metal oxide containing chromium, carbon and oxygen, and The second layer includes metal nitride oxide containing chromium, carbon, oxygen and nitrogen.

4. A photomask comprising: substrate; as well as a plurality of patterns, wherein the plurality of patterns are arranged on the substrate, wherein the pattern comprises a first layer and a second layer having different electrical conductivities, and Wherein, the electrical conductivity of the pattern is 500 S / cm to 2000 S / cm.

5. The photomask according to claim 4, wherein: The electrical conductivity of the pattern is 1200 S / cm to 1600 S / cm.

6. The photomask according to claim 4, wherein: The discharge voltage of the pattern is 400V to 550V.

7. The photomask according to claim 4, wherein: The discharge current of the pattern is 0.5 mA to 2 mA.

8. The photomask according to claim 4, wherein: The oxygen content of the first layer is different from the oxygen content of the second layer.

9. The photomask according to claim 4, wherein: The electrical conductivity of the first layer and the electrical conductivity of the second layer are different.

10. The photomask according to claim 4, wherein: The thickness of the first layer is greater than the thickness of the second layer.

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