JP2018132669A - Haze removal method and method of manufacturing photomask - Google Patents

Abstract

PROBLEM TO BE SOLVED: To remove a new kind of HAZE which cannot be removed by a method using a cleaning technique using ozone water or hydrogen water without using sulfuric acid or a method of irradiating ArF light under specific conditions. The main purpose is to provide a method for removing hydrogen water and a method for manufacturing a photomask. SOLUTION: A new kind of HAZE which cannot be removed by a conventional method is removed by a plasma treatment step using oxygen gas or chlorine gas, or oxygen gas and chlorine gas. [Selection diagram] Fig. 1

Description

  The present invention relates to a method for removing HAZE (fogging) generated in a photomask in an exposure process in a lithography technique using a photomask, and in particular, a method using a cleaning technique that does not use sulfuric acid such as ozone water or hydrogen water, The present invention relates to a new type of HAZE removal method that cannot be removed by a method of irradiating ArF light under specific conditions, and a method of manufacturing a photomask provided with this removal method.

In the manufacture of semiconductor devices, a photolithography technique is used in which a mask pattern formed on a photomask is transferred onto a wafer by an optical projection exposure apparatus.
As semiconductor devices are highly integrated and miniaturized, exposure light used in projection exposure apparatuses has also become shorter in wavelength, and ArF light having a wavelength of 193 nm is currently used as mainstream exposure light.

A photomask used for manufacturing such a semiconductor device is provided with a member called a pellicle composed of a transparent film that transmits exposure light in order to prevent pattern transfer failure due to adhesion of foreign matter.
By attaching this pellicle, foreign matter can be prevented from adhering to the surface of the photomask. In addition, even if fine foreign matter adheres to the pellicle's transparent film (called pellicle film), the surface of the pellicle and the surface of the photomask differ in principle from the focal plane of the optical system of the projection exposure apparatus. Foreign matter is not imaged on the wafer.

However, even in a photomask with a pellicle mounted, a phenomenon occurs in which foreign matter that grows with the exposure time is generated on the surface of the photomask, resulting in pattern transfer failure.
This growth foreign matter is called HAZE (also called haze), and it has been pointed out that the shorter the exposure light is, the more prominent it is.

  As one of the causes of such HAZE, sulfate ions, which are acidic substances used for photomask cleaning, remain on the photomask surface, and the sulfate ions and ammonia present in the photomask use environment, etc. It is considered that a basic substance reacts with exposure light to produce ammonium sulfate or the like to become a growth foreign substance (for example, Patent Document 1).

  In addition, although this HAZE has grown to the extent that it is recognized as a foreign substance (for example, having a size of 55 nm or more), it can be detected by a foreign substance inspection apparatus for a photomask, etc., but becomes a core of HAZE before growth. Substances such as sulfate ions cannot be detected even by inspection using an SEM (scanning electron microscope).

  For this reason, the use of a solution such as sulfuric acid / hydrogen peroxide (mixed solution of sulfuric acid and hydrogen peroxide solution) or ammonia / hydrogen peroxide solution (mixed solution of ammonia water and hydrogen peroxide solution), which has been used for cleaning photomasks, is conventionally used. Instead of this, a cleaning technique that does not use sulfuric acid with ozone water or hydrogen water has been developed (for example, Patent Documents 2 and 3).

  In recent years, there is a concern that organic HAZE may be generated by the oxidation of organic substances by ozone generated by exposure in a closed space between the pellicle film and the photomask. A method of decomposing C═C bonds by irradiation under specific conditions has been proposed (for example, Patent Document 4).

JP 2008-51880 A Japanese Patent Laid-Open No. 10-62965 JP 2000-330262 A JP 2009-294432 A

  However, in recent years, the photomask has been used for a longer period of time, and as the photomask is used longer, in other words, as the exposure time of the photomask increases, the above-described method, that is, ozone water. It has been confirmed that a new type of HAZE that cannot be removed by a method using a cleaning technique that does not use sulfuric acid such as hydrogen water or a method that irradiates ArF light under specific conditions has been confirmed.

  The present invention has been made in view of the above circumstances, and a main object of the present invention is to provide a HAZE removal method and a photomask manufacturing method capable of removing this new type of HAZE.

  The invention according to claim 1 of the present invention is a method of removing HAZE generated on the surface of a photomask by exposure, wherein the HAZE is obtained by a plasma treatment process using oxygen gas or chlorine gas, or oxygen gas and chlorine gas. It is a removal method of HAZE characterized by including the process of removing.

  According to a second aspect of the present invention, there is provided a mask pattern in which the photomask is made of a material including any one of molybdenum silicide (MoSi), silicon nitride (SiN), and tantalum (Ta). The method for removing HAZE according to claim 1, comprising:

  In the invention according to claim 3 of the present invention, the photomask has a light shielding frame pattern that defines an exposure region, and the light shielding frame is formed on the light shielding frame pattern before the plasma processing step. 3. The method of removing HAZE according to claim 1, further comprising a step of forming a resist pattern for protecting the pattern.

  The invention according to claim 4 of the present invention is the method for removing HAZE according to claim 3, wherein the surface of the light shielding frame pattern is composed of a layer containing chromium (Cr). .

  Further, the invention according to claim 5 of the present invention includes an inspection step of detecting the HAZE and a step of forming a resist pattern in order before the plasma treatment step, and the step of forming the resist pattern includes 2. The method of removing HAZE according to claim 1, wherein the method is a step of forming a resist pattern having an opening at a position where the HAZE detected in the inspection step exists.

  According to a sixth aspect of the present invention, the HAZE removal step using the HAZE removal method according to any one of the first to fifth aspects and the step of attaching a pellicle are sequentially performed. It is a manufacturing method of a photomask characterized by comprising.

  According to the HAZE removal method of the present invention, a new type of HAZE that cannot be removed by the conventional method can be removed.

  Moreover, according to the photomask manufacturing method of the present invention, a photomask from which a new type of HAZE that cannot be removed by the conventional method can be manufactured.

The flowchart which shows an example of 1st Embodiment of the manufacturing method of the photomask which concerns on this invention. Schematic process drawing showing an example of a first embodiment of a photomask manufacturing method according to the present invention The flowchart which shows an example of 2nd Embodiment of the manufacturing method of the photomask which concerns on this invention. Schematic process drawing showing an example of a second embodiment of a photomask manufacturing method according to the present invention FIG. 4 is a schematic process chart showing an example of the second embodiment of the photomask manufacturing method according to the present invention, following FIG. The flowchart which shows an example of 3rd Embodiment of the manufacturing method of the photomask which concerns on this invention. Schematic process drawing showing an example of a third embodiment of a photomask manufacturing method according to the present invention Schematic process drawing showing an example of the third embodiment of the photomask manufacturing method according to the present invention, following FIG. The figure shown about Example 1 The figure shown about Example 2

(First embodiment)
First, a first embodiment of a HAZE removal method and a photomask manufacturing method according to the present invention will be described. This embodiment is suitable, for example, in a binary photomask (so-called MoSi-based binary photomask) whose mask pattern is made of molybdenum silicide (MoSi).

  FIG. 1 is a flowchart showing an example of a first embodiment of a photomask manufacturing method according to the present invention. FIG. 2 is a schematic process diagram showing an example of the first embodiment of the photomask manufacturing method according to the present invention.

  In order to obtain a photomask 1 with a pellicle from which HAZE has been removed according to the present embodiment, first, as shown in FIGS. 2A and 2B, a photomask with a pellicle in which a new type of HAZE 50 as described above is generated. The pellicle 40 is peeled from 1A (S1 in FIG. 1).

  Here, as shown in FIG. 2A, the pellicle-equipped photomask 1 </ b> A has a configuration in which the pellicle 40 is mounted on the photomask 10 via an adhesive material 31. A plurality of HAZE 50 are generated.

  The pellicle 40 mainly includes a pellicle film 42 and a pellicle frame 41 that supports the pellicle film 42.

  The photomask 10 has a transparent substrate 11 and a mask pattern 12 as main components. The transparent substrate 11 is made of a material that transmits exposure light, and is typically a synthetic quartz substrate. The mask pattern 12 shields exposure light, and examples of the material thereof include a material containing any one of molybdenum silicide (MoSi), silicon nitride (SiN), and tantalum (Ta). it can.

  The HAZE 50 is generated not only on the mask pattern 12 of the photomask 10 but also on the edge of the mask pattern 12 and on the transparent substrate 11 exposed from the mask pattern 12. There are several thousand pieces.

As shown in FIG. 2B, the adhesive material 31 remains on the surface of the photomask 10 from which the pellicle 40 has been peeled off. Therefore, the remaining adhesive material 31 is removed by washing (S2 in FIG. 1).
A cleaning technique that does not use sulfuric acid such as ozone water or hydrogen water can be suitably used for the step of removing the adhesive material 31.

  Next, as shown in FIG. 2 (c), oxygen gas or chlorine gas, or on the surface of the photomask 10 having the HAZE 50 remaining after the step of removing the adhesive material 31 (S2 in FIG. 1), or Plasma treatment using oxygen gas and chlorine gas is performed to remove the HAZE 50 so that the form shown in FIG. 2D is obtained (S3 in FIG. 1).

For example, when the material constituting the mask pattern 12 is molybdenum silicide (MoSi), either oxygen gas or chlorine gas can be used to remove the HAZE 50.
On the other hand, when the material constituting the mask pattern 12 is a material that is etched with chlorine gas, it is preferable to use only oxygen gas.
Although the structure of the new type of HAZE 50 is not clear, it disappears by performing plasma treatment using oxygen gas or chlorine gas, so it is assumed that it has an organic bond structure.

For the plasma treatment, for example, an ICP (Inductively Coupled Plasma) type dry etching apparatus used for manufacturing a photomask can be used.
As the processing conditions, for example, the bias power can be set to 1 W to 30 W, the ICP power can be set to 10 W to 1000 W, the gas flow rate can be set to 50 ml / min to 200 ml / min, and the processing time can be set to each range of 30 seconds to 1500 seconds.

Moreover, when using only oxygen gas, the ashing apparatus used for photomask manufacture can be used, for example.
As the processing conditions, for example, the RF power is 50 W to 500 W, the gas flow rate is 50 ml / min to 200 ml / min, the processing time is 30 strokes to 600 seconds, and the pressure is 10 Pa to 90 Pa.

  Next, an inspection is performed to confirm that the HAZE 50 that affects the pattern transfer has been removed (S4 in FIG. 1). For this inspection, an inspection device used for inspection of foreign matter on the photomask can be used. For example, a 55 nm size foreign object can be detected by a transmission / reflection simultaneous inspection using light having a wavelength of 193 nm.

On the other hand, if it is confirmed in the above inspection (S4 in FIG. 1) that the HAZE 50 affecting the pattern transfer remains, the above HAZE removal (S3 in FIG. 1) is performed again and the above inspection is performed again. (S4 in FIG. 1) is performed.
The HAZE removal (S3 in FIG. 1) and inspection (S4 in FIG. 1) steps are repeated until it is confirmed that the HAZE 50 affecting the pattern transfer has been removed.

After confirming that the HAZE 50 affecting the pattern transfer has been removed, shipping cleaning is performed (S5 in FIG. 1), and a new pellicle 40 is mounted (S6 in FIG. 1), as shown in FIG. 2 (e). As described above, the pellicle-equipped photomask 1 from which the HAZE 50 is removed can be obtained. The photomask with pellicle 1 is shipped after the final inspection (S7 in FIG. 1).
For the above-described shipping cleaning (S5 in FIG. 1), a cleaning technique that does not use sulfuric acid such as ozone water or hydrogen water can be suitably used.

(Second Embodiment)
Next, a second embodiment of the HAZE removing method and the photomask manufacturing method according to the present invention will be described. This embodiment is suitable for a halftone phase shift photomask, for example.

  FIG. 3 is a flowchart showing an example of the second embodiment of the photomask manufacturing method according to the present invention. 4 and 5 are schematic process diagrams showing an example of the second embodiment of the photomask manufacturing method according to the present invention.

  In order to obtain the photomask 2 with a pellicle from which the HAZE has been removed according to the present embodiment, first, as shown in FIGS. 4A and 4B, the photomask with a pellicle in which the above new type of HAZE50 is generated The pellicle 40 is peeled from 2A (S1 in FIG. 3).

  Here, as shown in FIG. 4A, the pellicle-equipped photomask 2A has a configuration in which the pellicle 40 is mounted on the photomask 20 via the adhesive material 31. A plurality of HAZE 50 are generated.

  The pellicle 40 has, as a main configuration, a pellicle film 42 and a pellicle frame 41 that supports the pellicle film 42.

  The photomask 20 has a transparent substrate 21 and a mask pattern 22 as main components, and further has a light shielding film pattern 23. More specifically, the photomask 20 is a halftone phase shift photomask, and in addition to the halftone mask pattern 22, a light shielding film pattern 23 is formed on the mask pattern 22 as a light shielding frame pattern that defines an exposure region. The light shielding frame pattern has a structure in which the layers are stacked.

The transparent substrate 21 is made of a material that transmits exposure light, and is typically a synthetic quartz substrate.
The halftone mask pattern 22 transmits exposure light with a predetermined transmittance, and examples of the material thereof include a material containing molybdenum silicide (MoSi), silicon nitride (SiN), and the like.

  The light shielding film pattern 23 is a layered structure with the underlying mask pattern 22 and constitutes a light shielding frame pattern that shields exposure light. Examples of the material thereof include chromium (Cr), molybdenum silicide (MoSi), The thing containing silicon (Si), tantalum (Ta), etc. can be mentioned.

  For example, when a material including molybdenum silicide (MoSi) is used as the material of the mask pattern 22, a material including chromium (Cr) is generally used as the material of the light shielding film pattern 23.

  The HAZE 50 is generated not only on the mask pattern 22 of the photomask 20 but also on the edge of the mask pattern 22 and on the transparent substrate 21 exposed from the mask pattern 22. There are several thousand pieces.

As shown in FIG. 4B, the adhesive material 31 remains on the surface of the photomask 20 from which the pellicle 40 has been peeled off. Therefore, the remaining adhesive material 31 is removed by washing (S2 in FIG. 3).
A cleaning technique that does not use sulfuric acid such as ozone water or hydrogen water can be suitably used for the step of removing the adhesive material 31.

Here, as shown in FIG. 4C, a light shielding film pattern 23 also exists on the surface of the photomask 20 from which the adhesive material 31 has been removed.
As described above, when a material containing molybdenum silicide (MoSi) is used as the material of the mask pattern 22, a material containing chromium (Cr) is generally used as the material of the light shielding film pattern 23.

However, chromium (Cr), when subjected to plasma treatment using oxygen gas and chlorine gas, may be etched to impair the function as a light shielding film. Similarly, even plasma processing using only chlorine gas may be etched.
Further, even when plasma treatment using only oxygen gas is performed, ozone is generated, and there is a possibility that film loss occurs due to this ozone.

Such a problem is a problem that occurs when a material that is damaged by plasma treatment using oxygen gas or chlorine gas is used for the light shielding film pattern 23 in addition to chromium (Cr).
Therefore, in this embodiment, after the step of removing the adhesive material 31 (S2 in FIG. 3), the step of removing the HAZE 50 by the plasma treatment using oxygen gas or chlorine gas as described above (FIG. 3). Before S4), as shown in FIG. 4D, a resist pattern 61 for protecting the light shielding film pattern 23 is formed on the light shielding film pattern 23 (S3 in FIG. 3).
As a method of forming the resist pattern 61, for example, a method of spin-coating a resist for laser drawing, laser drawing so as to obtain a desired pattern, and performing a process such as development can be given.

  By this resist pattern 61, for example, even when the surface layer of the light shielding frame pattern is made of a material that is damaged by the plasma treatment using oxygen gas or chlorine gas, the surface layer can be protected. it can.

  Next, as shown in FIG. 4D, oxygen gas or chlorine gas, or oxygen gas and chlorine gas is used on the surface of the photomask 20 in which the resist pattern 61 is formed on the light shielding film pattern 23. The HAZE 50 is removed so that the form shown in FIG. 4E is obtained (S4 in FIG. 3).

  For this plasma treatment, for example, an ICP (Inductively Coupled Plasma) type dry etching apparatus used for manufacturing a photomask can be used. As treatment conditions, for example, bias power is 1 W to 30 W, and ICP power is 10 W to 10 W. 1000 W, gas flow rate 50 ml / min to 200 ml / min, and processing time can be in the range of 30 seconds to 1500 seconds.

  Further, when only oxygen gas is used, for example, an ashing apparatus used for photomask manufacture can be used. As processing conditions, for example, RF power is 50 W to 500 W, and gas flow rate is 50 ml / min to 200 ml. / Min, the treatment time can be in the range of 30 strokes to 600 seconds, and the pressure can be in the ranges of 10 Pa to 90 Pa.

For example, when the material constituting the mask pattern 22 is molybdenum silicide (MoSi), either oxygen gas or chlorine gas can be used to remove the HAZE 50.
On the other hand, when the material constituting the mask pattern 22 is an object etched with chlorine gas, it is preferable to use only oxygen gas.

Next, as shown in FIG. 5F, the resist pattern 61 is removed (S5 in FIG. 3).
For removing the resist pattern 61, an ashing technique using oxygen gas, which is used in photomask manufacturing, can be used. Moreover, you may remove using a solvent etc.

  Further, it is preferable to subsequently perform cleaning (S6 in FIG. 3). This is because the remaining resist and newly attached foreign matters can be removed more effectively. For this cleaning, a cleaning technique that does not use sulfuric acid such as ozone water or hydrogen water can be suitably used.

  Next, an inspection is performed to confirm that the HAZE 50 that affects the pattern transfer has been removed (S7 in FIG. 3). For this inspection, an inspection device used for inspection of foreign matter on the photomask can be used. For example, a 55 nm size foreign object can be detected by a transmission / reflection simultaneous inspection using light having a wavelength of 193 nm.

On the other hand, if it is confirmed in the above inspection (S7 in FIG. 3) that the HAZE 50 that affects the pattern transfer remains, the resist pattern 61 is formed again (S3 in FIG. 3). A series of steps of removing the HAZE 50 (S4 in FIG. 3), removing the resist pattern 61 (S5 in FIG. 3), and cleaning (S6 in FIG. 3) are performed, and the above inspection (S7 in FIG. 3) is performed again.
The steps from the resist pattern formation (S3 in FIG. 3) to the inspection (S7 in FIG. 3) are repeated until it is confirmed that the HAZE 50 affecting the pattern transfer has been removed.

After confirming that the HAZE 50 affecting the pattern transfer has been removed, shipping cleaning is performed (S8 in FIG. 3), and a new pellicle 40 is mounted (S9 in FIG. 3), as shown in FIG. 5 (g). As described above, the pellicle-equipped photomask 2 from which the HAZE 50 is removed can be obtained. The photomask 2 with a pellicle is shipped after the final inspection (S10 in FIG. 3).
In the above-described shipping cleaning (S8 in FIG. 3), a cleaning technique that does not use sulfuric acid such as ozone water or hydrogen water can be suitably used.

(Third embodiment)
Next, a third embodiment of the HAZE removal method and photomask manufacturing method according to the present invention will be described.
In the present embodiment, an inspection process for detecting HAZE and a process for forming a resist pattern are sequentially provided before the plasma processing process for removing HAZE. The step of forming the resist pattern is a step of forming a resist pattern having an opening at a position where the HAZE detected in the inspection step exists.

  FIG. 6 is a flowchart showing an example of the third embodiment of the photomask manufacturing method according to the present invention. 7 and 8 are schematic process diagrams showing an example of the third embodiment of the photomask manufacturing method according to the present invention.

  The photomask in the example shown in FIGS. 7 and 8 is a halftone phase shift photomask having a light shielding film pattern 23 as in the photomask 20 shown in FIGS. The present embodiment is not limited to this, and may be, for example, a binary photomask similar to the photomask 10 shown in FIG.

In order to obtain the photomask 2 with the pellicle from which the HAZE has been removed according to the present embodiment, first, as shown in FIGS. 7A and 7B, the photomask with a pellicle in which the new type of HAZE 50 as described above is generated. The pellicle 40 is peeled from 2A (S1 in FIG. 6), and then the remaining adhesive material 31 is removed by washing (S2 in FIG. 6).
A cleaning technique that does not use sulfuric acid such as ozone water or hydrogen water can be suitably used for the step of removing the adhesive material 31.

  Next, inspection is performed to detect the HAZE 50 that affects the pattern transfer (S3 in FIG. 6). For this inspection, an inspection device used for inspection of foreign matter on the photomask can be used. For example, a 55 nm size foreign object can be detected by a transmission / reflection simultaneous inspection using light having a wavelength of 193 nm.

  In the example shown in FIG. 6, this inspection is performed after removal of the adhesive material (S2 in FIG. 6), but it is also possible to perform this inspection before the peeling of the pellicle (S1 in FIG. 6). For example, in the case of the inspection apparatus used for the above-described photomask foreign matter inspection, foreign matter present on the surface of the photomask with the pellicle mounted can also be detected.

Next, as shown in FIG. 7D, a resist pattern 62 having an opening at the position where the HAZE 50 detected by the above inspection (S3 in FIG. 6) exists is formed.
As a method of forming the resist pattern 62, for example, a method of spin-coating a resist for laser drawing, laser drawing so as to obtain a desired pattern, and performing a process such as development can be given.

Normally, the HAZE 50 has a very fine size, and the size is smaller than the minimum dimension that can be laser-drawn. However, the planar size of the opening should be such that the detected HAZE 50 is exposed. For example, as shown in FIG. 7D, the size may be such that a region where a plurality of HAZEs 50 are present is exposed collectively.
Therefore, the resist pattern 62 can be sufficiently used even if it is a resist pattern formed by laser drawing.

  On the other hand, the resist pattern 62 can protect the mask pattern 22 and the transparent substrate 21 in the region where the HAZE 50 is not present from the plasma processing for removing the HAZE. Moreover, when the light shielding frame pattern exists, the surface layer (for example, the light shielding film pattern 23 in FIGS. 7 and 8) can be protected.

  Next, the surface of the photomask 20 on which the resist pattern 62 is formed is subjected to plasma treatment using oxygen gas or chlorine gas, or oxygen gas and chlorine gas, so that the configuration shown in FIG. , HAZE50 is removed (S5 in FIG. 6).

  For this plasma treatment, for example, an ICP (Inductively Coupled Plasma) type dry etching apparatus used for manufacturing a photomask can be used. As treatment conditions, for example, bias power is 1 W to 30 W, and ICP power is 10 W to 10 W. 1000 W, gas flow rate 50 ml / min to 200 ml / min, and processing time can be in the range of 30 seconds to 1500 seconds.

  Further, when only oxygen gas is used, for example, an ashing apparatus used for photomask manufacture can be used. As processing conditions, for example, RF power is 50 W to 500 W, and gas flow rate is 50 ml / min to 200 ml. / Min, the treatment time can be in the range of 30 strokes to 600 seconds, and the pressure can be in the ranges of 10 Pa to 90 Pa.

For example, when the material constituting the mask pattern 22 is molybdenum silicide (MoSi), either oxygen gas or chlorine gas can be used to remove the HAZE 50.
On the other hand, when the material constituting the mask pattern 22 is an object etched with chlorine gas, it is preferable to use only oxygen gas.

Next, the resist pattern 62 is removed as shown in FIG. 8F (S6 in FIG. 6).
For removing the resist pattern 61, ashing using oxygen gas can be used. Moreover, you may remove using a solvent etc.

  Further, it is preferable to subsequently perform cleaning (S7 in FIG. 6). This is because the remaining resist and newly attached foreign matters can be removed more. For this cleaning, a cleaning technique that does not use sulfuric acid such as ozone water or hydrogen water can be suitably used.

  Next, an inspection is performed to confirm that the HAZE 50 that affects the pattern transfer has been removed (S8 in FIG. 6). As described above, this inspection can also be performed using an inspection apparatus used for inspection of foreign matter on a photomask.

In the above inspection (S8 in FIG. 6), when it is confirmed that the HAZE 50 that affects the pattern transfer remains, the resist pattern 62 is formed again (S4 in FIG. 6). A series of steps of removal (S5 in FIG. 6), removal of the resist pattern 62 (S6 in FIG. 6), and cleaning (S7 in FIG. 6) are performed, and the above inspection (S8 in FIG. 6) is performed again.
The steps from this resist pattern formation (S4 in FIG. 6) to the inspection (S8 in FIG. 6) are repeated until it is confirmed that the HAZE 50 affecting the pattern transfer has been removed.

After confirming that the HAZE 50 affecting the pattern transfer has been removed, shipping cleaning is performed (S9 in FIG. 6), and a new pellicle 40 is mounted (S10 in FIG. 6), as shown in FIG. 8 (g). As described above, the pellicle-equipped photomask 2 from which the HAZE 50 is removed can be obtained. The photomask 2 with a pellicle is shipped after the final inspection (S11 in FIG. 6).
In the above-described shipping cleaning (S9 in FIG. 6), a cleaning technique that does not use sulfuric acid such as ozone water or hydrogen water can be suitably used.

  As mentioned above, although each embodiment was described about the removal method of HAZE which concerns on this invention, and the manufacturing method of a photomask, this invention is not limited to the said embodiment. The above-described embodiment is an exemplification, and the present invention has substantially the same configuration as the technical idea described in the claims of the present invention and exhibits the same function and effect regardless of the case. Are included in the technical scope.

  Hereinafter, the present invention will be described more specifically with reference to examples.

Example 1
In Example 1, an example in which HAZE generated in a binary photomask is removed by plasma processing using oxygen gas based on the first embodiment will be described.

First, the pellicle was peeled from the photomask with a pellicle in which HAZE was generated, and washed with ozone water and hydrogen water to remove the adhesive material.
FIG. 9A shows an SEM photograph of the photomask surface after peeling the pellicle, and FIG. 9B shows an SEM photograph of the photomask surface after removing the adhesive material.
As shown in FIG. 9B, HAZE that could not be removed by cleaning with ozone water and hydrogen water remains on the photomask surface.
Here, the remaining HAZE can be discriminated from an image projected by an SEM if it is an expert, but it is often difficult for an amateur to discriminate this HAZE from an SEM photograph so as to be called “cloudy”. . The same applies to FIG. Therefore, as a supplement, in FIG. 9A, a portion where HAZE remains is indicated by a white broken circle.

  In this photomask, a synthetic quartz glass substrate having a planar size of 152 mm square and a thickness of 6.35 mm is used as a transparent substrate, and a light shielding pattern made of molybdenum silicide (MoSi) is formed thereon as a mask pattern. Binary type photomask.

Next, the surface of the photomask was subjected to plasma treatment using oxygen gas to remove HAZE.
For this plasma treatment, an ashing apparatus used for manufacturing a photomask was used. The treatment conditions were an RF power of 300 W, an oxygen gas flow rate of 100 ml / min, a treatment time of 200 seconds, and a pressure of 40 Pa.

An SEM photograph of the photomask surface after the removal of HAZE is shown in FIG.
As shown in FIG. 9C, it was confirmed that HAZE that could not be removed by cleaning with ozone water and hydrogen water was removed.

(Example 2)
In Example 2, an example in which HAZE generated in a halftone phase shift photomask is removed by plasma treatment using oxygen gas and chlorine gas based on the second embodiment will be described.

First, the pellicle was peeled from the photomask with a pellicle in which HAZE was generated, and washed with ozone water and hydrogen water to remove the adhesive material.
FIG. 10A shows a SEM photograph of the photomask surface after peeling the pellicle, and FIG. 10B shows a SEM photograph of the photomask surface after the adhesive material removal cleaning.
As shown in FIG. 10B, HAZE that could not be removed by cleaning with ozone water and hydrogen water remains.
Here, as described above, it is often difficult for an amateur to determine the remaining HAZE from an SEM photograph. Therefore, as in FIG. 9 (a), in FIG. 10 (a), the remaining portion of the HAZE is indicated by a white broken circle.

The photomask is a halftone phase shift photomask. First, a synthetic quartz glass substrate having a planar size of 152 mm square and a thickness of 6.35 mm is used as a transparent substrate, and a mask pattern is formed thereon. A halftone mask pattern made of molybdenum silicide (MoSi) is formed.
Further, as a light shielding frame pattern for defining an exposure region, a light shielding frame pattern having a structure in which a light shielding film pattern made of chromium (Cr) is stacked on the mask pattern made of molybdenum silicide (MoSi) is formed. Has been.

  Next, a resist for laser drawing is spin-coated on the surface of the photomask, and laser drawing, development, and other processes are performed to form a resist pattern having a thickness of 350 nm on the light shielding frame pattern of the laminated structure. .

Next, the surface of the photomask on which the resist pattern was formed was subjected to plasma treatment using a mixed gas of chlorine gas and oxygen gas.
For this plasma treatment, an ICP (Inductively Coupled Plasma) type dry etching apparatus used for manufacturing a photomask is used. The treatment conditions are a bias power of 6 W, an ICP power of 250 W, a mixing ratio of chlorine gas and oxygen gas of 2: 1, The gas flow rate was 100 ml / min, and the processing time was 700 seconds.

FIG. 10C shows an SEM photograph of the photomask surface after this HAZE removal.
As shown in FIG. 10C, it was confirmed that HAZE that could not be removed by cleaning with ozone water and hydrogen water was removed.

1, 2 Photomasks with pellicles 1A, 2A Photomasks with pellicle 10, 20 Photomasks 11, 21 Transparent substrate 12, 22 Mask pattern 23 Light shielding film pattern 31 Adhesive material 40 Pellicle 41 Pellicle frame 42 Pellicle film 50 HAZE
61, 62 Resist pattern

Claims (6)

A method for removing HAZE generated on the surface of a photomask by exposure comprising:
A method for removing HAZE, comprising a step of removing the HAZE by a plasma treatment process using oxygen gas or chlorine gas, or oxygen gas and chlorine gas.   2. The photomask according to claim 1, wherein the photomask has a mask pattern made of a material containing any one of molybdenum silicide (MoSi), silicon nitride (SiN), and tantalum (Ta). Method for removing HAZE. The photomask has a light shielding frame pattern that defines an exposure region;
The HAZE removing method according to claim 1, further comprising a step of forming a resist pattern that protects the light shielding frame pattern on the light shielding frame pattern before the plasma treatment step. .   4. The method of removing HAZE according to claim 3, wherein the surface of the light shielding frame pattern is composed of a layer containing chromium (Cr). Before the plasma treatment step, an inspection step for detecting the HAZE and a step of forming a resist pattern are sequentially provided,
2. The method of removing HAZE according to claim 1, wherein the step of forming the resist pattern is a step of forming a resist pattern having an opening at a position where the HAZE detected in the inspection step exists. . A step of removing HAZE using the method of removing HAZE according to any one of claims 1 to 5,
Attaching the pellicle; and
In order. The manufacturing method of the photomask characterized by the above-mentioned.