JP2015161834A - Photomask production method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a photomask production method which has optical characteristics, light fastness and washing resistance comparable with those of materials constituting mask patterns and enables correction of deficiencies and defects without a correction material and production of a photomask free of deficiencies and defects.SOLUTION: A method of producing a photomask comprises forming a second thin film 13A easier in defect correction than a first thin film 12A on the first thin film 12A, conducting defect inspection at the stage when the second thin film 13A is processed to form a second thin film pattern 13, correcting a detected deficiency defect part 21 of the second thin film pattern and processing, by etching, the first thin film 12A exposed from the second thin film pattern 13 with the defect corrected to form a first thin film pattern 12.

Description

  The present invention relates to a method for manufacturing a photomask used for manufacturing a semiconductor element, and more particularly to a defect defect correcting technique for a photomask.

  Currently, higher integration and miniaturization of semiconductor elements have progressed from a 45 nm node to a 32 nm node in the design rule, and further development of semiconductor elements having a node of 22 nm or less is underway. In order to realize high integration and miniaturization of semiconductor elements, a mask pattern of a photomask is reduced and formed on a wafer by an optical projection exposure apparatus using an ArF excimer laser having a wavelength of 193 nm. Photolithographic technology is used.

A photomask (also referred to as a reticle) used in photolithography technology is a binary in which a light-shielding film made of chromium (Cr) or the like is formed on a transparent substrate, and a pattern is composed of a portion that transmits light and a portion that blocks light In addition to a type photomask (hereinafter also referred to as a binary mask), there is a phase shift mask that improves resolution by a phase shift effect using light interference.
This phase shift mask has a Levenson-type phase shift mask with a configuration in which the phase of light is alternately inverted across the mask pattern, and a halftone phase shift with a configuration in which the phase is inverted between the light transmitting portion and the semi-transmitting portion There are masks, chromium-less phase shift masks and the like that are not provided with a light-shielding layer such as chromium. Among them, halftone masks are frequently used because they do not require a special pattern shifter and can be manufactured using conventional mask data.

The above halftone phase shift mask has a mask pattern (hereinafter also referred to as a semitransparent mask pattern) made of a semitransparent film on a transparent substrate as a normal configuration, and this semitransparent mask pattern is provided. It is designed so that the phase of the light transmitted through the part and the light transmitted through the part where the transparent substrate is exposed are reversed.
In such a halftone phase shift mask, the light intensity decreases due to phase inversion at the boundary between the portion where the translucent mask pattern is provided and the portion where the transparent substrate is exposed, and the tail of the light intensity distribution is widened. Can be suppressed. As a material for the translucent mask pattern, a compound mainly containing molybdenum silicide (MoSi), such as molybdenum oxynitride silicide (MoSiON), is widely used (for example, Patent Document 1).

Here, in the manufacture of a photomask including a phase shift mask, a residue defect (also referred to as a black defect), which is an unnecessary surplus portion, may occur in the mask pattern. The process of removing this residue defect portion is a black defect correction. This is called a process.
In addition, a defective defect (also referred to as a white defect) in which a part of a necessary mask pattern is lost may occur. For example, a correction material may be applied to the defective defect portion using a deposition gas and an electron beam. The process of depositing is called a white defect correction process.

  The manufacturing process of a photomask including a phase shift mask includes many complicated processes, and the mask pattern is extremely fine. Both in terms of manufacturing cost and manufacturing cost. Therefore, in the manufacture of a photomask including a phase shift mask, the defect correction as described above is an essential process (for example, Patent Document 2).

JP2013-11900A JP 2004-294613 A

However, in correcting the defect, the correction material to be deposited is required to have optical characteristics, light resistance, cleaning resistance, etc. equivalent to those of the mask pattern.
In particular, in the conventional halftone phase shift mask, as described above, the translucent mask pattern is composed of a compound containing molybdenum silicide (MoSi). However, the deposition capable of depositing molybdenum silicide (MoSi) is possible. Since there is no working gas, a material different from molybdenum silicide (MoSi) can only be used as a correction material, and any of optical properties, light resistance, and cleaning resistance is insufficient and problematic It was.

  The present invention has been made in view of the above circumstances, and enables defect defects to be corrected without requiring a correction material having the same optical characteristics, light resistance, and cleaning resistance as the material constituting the mask pattern. It is an object of the present invention to provide a photomask manufacturing method capable of manufacturing a photomask having no defect.

  As a result of various researches, the present inventor formed a second thin film on the first thin film, which is easier to repair defects than the first thin film, and processed the second thin film to obtain the second thin film. Defect inspection is performed at the stage of forming the pattern, the defective defect portion of the detected second thin film pattern is corrected, and the first thin film exposed from the defect corrected second thin film pattern is etched to form the first thin film pattern. The present invention has been completed by finding that the above problems can be solved by forming a thin film pattern.

  That is, the invention according to claim 1 of the present invention includes a transparent substrate, a first thin film formed on the transparent substrate, and a second thin film formed on the first thin film. A step of preparing mask blanks, a step of etching the second thin film to form a second thin film pattern, a defect inspection step of detecting a defective defect portion of the second thin film pattern, and a first A correction material depositing step of depositing a correction material on the defective defect portion of the second thin film pattern detected in the defect inspection step by irradiating the first electron beam while supplying the deposition gas of And a step of forming the first thin film pattern by etching the first thin film exposed from the second thin film pattern on which the correction material is deposited.

  According to a second aspect of the present invention, there is provided a transparent substrate, a first thin film formed on the transparent substrate, and a second thin film formed on the first thin film. A step of preparing mask blanks, a step of etching the second thin film to form a second thin film pattern, a defect inspection step of detecting a defective defect portion of the second thin film pattern, and a first A correction material depositing step of depositing a correction material on the defective defect portion of the second thin film pattern detected in the defect inspection step by irradiating the first electron beam while supplying the deposition gas of Etching removal of the excess correction material deposited around the defect defect portion of the second thin film pattern by irradiating the second electron beam while supplying the first etching gas in the correction material deposition step. Excess correction material And a step of etching the first thin film exposed from the second thin film pattern from which the excess correction material has been removed to form a first thin film pattern. It is a manufacturing method.

  According to a third aspect of the present invention, there is provided a transparent substrate, a first thin film formed on the transparent substrate, and a second thin film formed on the first thin film. A step of preparing mask blanks, a step of etching the second thin film to form a second thin film pattern, and a defect inspection step of detecting a defective defect portion and a residual defect portion of the second thin film pattern And a correction material that deposits the correction material on the defect defect portion of the second thin film pattern detected in the defect inspection step by irradiating the first electron beam while supplying the first deposition gas. The surplus correction material deposited around the defect defect portion of the second thin film pattern by the deposition step and the correction material deposition step is irradiated with the second electron beam while supplying the first etching gas. Etching removal by Irradiating a third electron beam while supplying a second etching gas to the residual defect portion of the second thin film pattern detected in the defect correcting step and the surplus correcting material removing step A residue defect correcting step of etching away a residual defect portion of the second thin film pattern; and a first thin film pattern formed by etching the first thin film exposed from the second thin film pattern obtained by etching away the residual defect portion. And a step of forming a photomask.

  According to a fourth aspect of the present invention, in the correction material depositing step, the fourth electron beam is irradiated while supplying the second deposition gas, so that the defect defect portion is located at a different position. Using the deposit structure formed on the second thin film pattern as a positioning mark, the position of irradiation with the first electron beam is corrected, and the defect portion of the second thin film pattern is corrected. 4. The photomask manufacturing method according to claim 1, wherein a correction material is deposited.

  Further, the invention according to claim 5 of the present invention differs from the defect defect portion by irradiating a fourth electron beam while supplying the second deposition gas in the surplus correcting material removing step. Using the deposit structure formed on the second thin film pattern at the position as a positioning mark, correcting the position of irradiation with the second electron beam, the defect defect of the second thin film pattern 5. The photomask manufacturing method according to claim 2, wherein excess correction material deposited around the portion is removed by etching. 6.

  Further, the invention according to claim 6 of the present invention is a position different from the residue defect portion by irradiating the fourth electron beam while supplying the second deposition gas in the residue defect correction step. The deposit structure formed on the second thin film pattern is used as a positioning mark to correct the position of irradiation with the third electron beam, and the residual defect portion of the second thin film pattern The method for producing a photomask according to claim 3, wherein the step of etching is removed by etching.

In the invention according to claim 7 of the present invention, the atomic ratio (A _Mo / A _Si ) of molybdenum (Mo) to silicon (Si) in the first thin film is 0 ≦ A _Mo / A _Si ≦ 1 / The photomask manufacturing method according to claim 1, wherein the relationship 10 is satisfied.

  According to an eighth aspect of the present invention, the first thin film is one or more of a silicon oxide film (SiO), a silicon nitride film (SiN), and a silicon oxynitride film (SiON). The photomask manufacturing method according to claim 1, wherein the photomask manufacturing method comprises:

  In the invention according to claim 9 of the present invention, the second thin film is made of a material containing chromium (Cr), and the first deposition gas is a gas containing chromium (Cr). It is a manufacturing method of the photomask as described in any one of Claims 1 thru | or 8 characterized by the above-mentioned.

Further, in the invention according to claim 10 of the present invention, the gas containing chromium (Cr) is a gas containing chromium hexacarbonyl (Cr (CO) ₆ ). It is a manufacturing method.

  According to an eleventh aspect of the present invention, the first etching gas and the second etching gas are gases containing fluorine (F) or gases containing chlorine (Cl). A method for producing a photomask according to claim 9 or 10, wherein:

In the invention according to claim 12 of the present invention, the gas containing fluorine (F) is a gas containing xenon fluoride (XeF ₂ ), and the gas containing chlorine (Cl) is nitrosyl chloride (NOCl). The method of manufacturing a photomask according to claim 11, wherein the gas contains a gas.

In the invention according to claim 13 of the present invention, the first etching gas and the second etching gas are oxygen (O ₂ ), water vapor (H ₂ O), nitrogen dioxide (NO ₂ ), 13. The method for producing a photomask according to claim 11, wherein the photomask is a mixed gas to which any one or more of ammonium carbonate ((NH ₄ ) ₂ CO ₃ ) is added. It is.

  The invention according to claim 14 of the present invention is characterized in that the second deposition gas is a gas containing chromium (Cr) or a gas containing silicon (Si). It is a manufacturing method of the photomask as described in any one of thru | or thru | or 13.

In the invention according to claim 15 of the present invention, the gas containing chromium (Cr) is a gas containing chromium hexacarbonyl (Cr (CO) ₆ ), and the gas containing silicon (Si) is tetraethyl orthosilicate. The method of manufacturing a photomask according to claim 14, wherein the gas contains (Si (OC ₂ H ₅ ) ₄ ).

  According to the present invention, the defect defect can be corrected without being limited to the material constituting the mask pattern, and a photomask free from the defect defect can be manufactured.

It is a flowchart which shows an example of the manufacturing method of the photomask which concerns on this invention. It is a schematic process drawing which shows an example of 1st Embodiment of the manufacturing method of the photomask which concerns on this invention. It is a schematic process drawing which shows the other example of 1st Embodiment of the manufacturing method of the photomask which concerns on this invention. It is explanatory drawing which shows an example of the form of the defect defect based on this invention, and an example of the correction method. It is explanatory drawing which shows another example of the defect defect based on this invention, and an example of the correction method. It is explanatory drawing which shows the other example of the defect defect based on this invention following FIG. 5, and an example of the correction method. It is a schematic process drawing which shows an example of 2nd Embodiment of the manufacturing method of the photomask which concerns on this invention. FIG. 8 is a schematic process diagram illustrating an example of the second embodiment of the photomask manufacturing method according to the present invention following FIG. 7. It is a schematic process drawing which shows the other example of 2nd Embodiment of the manufacturing method of the photomask which concerns on this invention. FIG. 10 is a schematic process diagram illustrating another example of the second embodiment of the photomask manufacturing method according to the present invention following FIG. 9; It is explanatory drawing which shows the example of the form of the residue defect which concerns on this invention. It is a schematic process drawing which shows an example of 3rd Embodiment of the manufacturing method of the photomask which concerns on this invention. FIG. 13 is a schematic process diagram illustrating an example of the third embodiment of the photomask manufacturing method according to the present invention following FIG. 12. It is a schematic sectional drawing which shows the structural example of the phase shift mask which concerns on this invention.

  Hereinafter, a method for manufacturing a photomask according to the present invention will be described.

(Photomask manufacturing method)
FIG. 1 is a flowchart showing an example of a photomask manufacturing method according to the present invention.
As shown in FIG. 1, the method for manufacturing a photomask according to the present invention includes a step of preparing a mask blank in which a first thin film is formed on a transparent substrate and a second thin film is formed thereon (S1). ), Etching the second thin film of the mask blanks prepared in step S1 to form a second thin film pattern (S2), and detecting defective defects in the second thin film pattern formed in step S2. Defect inspection step (S3), defect correction step (S4) for correcting the defective defect portion of the second thin film pattern detected in step S3, and etching of the first thin film exposed from the second thin film pattern corrected in step S4 Each step of processing (S5) to form a first thin film pattern is provided in order.

Here, when the photomask is a halftone phase shift mask, the translucent layer corresponds to the first thin film, and when the photomask is a binary mask, the light shielding film is the above-described first thin film. This corresponds to the first thin film.
The second thin film serves as an etching mask when the first thin film is etched to form the first thin film pattern.
In the present invention, another layer may exist between the first thin film and the second thin film.
For example, the first thin film may be a translucent layer, the second thin film may be a hard mask, and a light shielding film or an etching stopper layer may be present between the first thin film and the second thin film. .
Moreover, another layer may exist between the transparent substrate and the first thin film or on the second thin film.
For example, an etching stopper layer or the like may exist under the first thin film.
Further, for example, when the second thin film also acts as a light shielding film, a form in which a hard mask layer for processing the second thin film is formed on the second thin film may be employed.

  Here, in the conventional method of manufacturing a phase shift mask, after the semitransparent mask pattern is formed, the semitransparent mask pattern is inspected to detect defective defects in the semitransparent mask pattern, and the detected semitransparent mask pattern The defect defect was corrected.

On the other hand, in the present invention, as described above, the second thin film pattern formed on the translucent layer is inspected to detect a defective defect portion of the second thin film pattern (S3), and the detected second thin film pattern is detected. The defect-defect portion of the thin-film pattern is corrected (S4), and then the first thin film exposed from the second thin-film pattern in which the defect-defect portion is corrected is etched so that the first thin film having no defect defect A pattern is formed (S5).
Therefore, in the present invention, it is possible to manufacture a photomask having no defect without being limited to the material constituting the first thin film pattern (that is, the mask pattern).
Hereinafter, embodiments of the present invention will be described in more detail with reference to process drawings.

(First embodiment)
First, a first embodiment of a photomask manufacturing method according to the present invention will be described with reference to FIG.

<Mask blanks preparation process>
As shown in FIG. 2A, in the present embodiment, first, the transparent substrate 11, the first thin film 12A formed on the transparent substrate 11, and the first thin film 12A are formed. A mask blank having the second thin film 13A is prepared.

[Transparent substrate]
As the transparent substrate 11, any material that transmits exposure light such as ArF excimer laser with high transmittance can be used, and examples thereof include synthetic quartz glass, fluorite, and calcium fluoride. From the results of the conventional phase shift mask, synthetic quartz glass can be preferably used.

[First thin film]
When the photomask is a halftone phase shift mask, the first thin film 12A corresponds to a semitransparent layer that acts as a halftone layer that controls the phase and transmittance of exposure light such as an ArF excimer laser. To do.
In the case where the first thin film 12A corresponds to the above-described semitransparent layer, with respect to the phase, the exposure light transmitted through the portion of the first thin film pattern 12 formed from the first thin film 12A and the transparent substrate 11 are exposed. It is designed so that the phase of the exposure light transmitted through the portion to be inverted is reversed.

  On the other hand, when the photomask is a binary mask, the first thin film 12A corresponds to a light shielding film. In this case, the first thin film 12A is usually designed so that the value of the optical density with respect to the exposure light is approximately 3.

In the present invention, the defect defect can be corrected without being limited to the material constituting the first thin film pattern (that is, the mask pattern), and a photomask having no defect defect can be manufactured.
Therefore, as the material of the first thin film 12A, for example, a material used for a semitransparent layer of a conventional halftone phase shift mask for ArF excimer laser or a light shielding film of a binary mask can be applied.
Furthermore, in the present invention, even a material different from the conventional material can be used as the material of the first thin film 12A as long as it can be etched as a mask pattern.

  For example, as the first thin film 12A, a molybdenum silicide (MoSi) -based material such as a molybdenum silicide oxide film (MoSiO), a molybdenum silicide nitride film (MoSiN), a molybdenum silicide oxynitride film (MoSiON), or the like can be used.

However, the translucent mask pattern made of a molybdenum silicide (MoSi) -based material having a conventional composition ratio does not have sufficient light resistance to ArF excimer laser exposure, and the mask dimensions change with the exposure time. was there.
This is because when the translucent layer contains a large amount of molybdenum (Mo), the oxidation of silicon (Si) is promoted, and as a result, a silicon oxide film grows on the surface of the translucent mask pattern and the mask dimension is increased. It is thought to change.

Therefore, in the present invention, the atomic ratio (A _Mo / A _Si ) between molybdenum (Mo) and silicon (Si) in the first thin film 12A is
0 ≦ A _Mo / A _Si ≦ 1/10
Those satisfying this relationship are preferable.
If the above relationship is satisfied, the first thin film 12A can be etched to form a first thin film pattern having high light resistance and high dimensional stability in ArF excimer laser exposure. It is.
The first thin film pattern 12 with improved light resistance is formed by subjecting the first thin film 12A with the improved material composition to dry etching using a fluorine-based gas similar to the conventional one. be able to.

  As a method of forming the first thin film 12A having a composition ratio satisfying the above relationship, for example, a mixed target of molybdenum and silicon or a silicon target not containing molybdenum is appropriately used, and a mixed gas of argon, nitrogen, and oxygen is used. It can be formed by reactive sputtering in an atmosphere.

  In the present invention, as the first thin film 12A, any one of a silicon oxide film (SiO), a silicon nitride film (SiN), and a silicon oxynitride film (SiON) that does not contain molybdenum (Mo) or A thin film comprising a plurality of types can be suitably used.

  By forming the translucent layer of the halftone phase shift mask for ArF excimer laser with a thin film made of the above-described material, a translucent mask pattern having high light resistance and high dimensional stability in ArF excimer laser exposure is formed. Because it can. Moreover, if it is a thin film which consists of said material, it can also have a high washing | cleaning tolerance.

Furthermore, by configuring the translucent layer of the halftone phase shift mask for ArF excimer laser with a thin film made of the above-mentioned material, the light transmittance can be increased to 15% or more, and the conventional light transmission of 6%. Compared with a translucent layer having a ratio, the phase effect can be made more prominent and the contrast of the transferred image can be further improved.
When the above material is used as the first thin film 12A, the first thin film pattern 12 can be formed by performing a dry etching process using a fluorine-based gas.

  As a method of forming the first thin film 12A made of the above material, for example, it is formed by a reactive sputtering method in a mixed gas atmosphere in which oxygen or nitrogen is appropriately contained in argon using a silicon target that does not contain molybdenum. Can do.

[Second thin film]
The second thin film 13A is for forming the second thin film pattern 13 that acts as an etching mask when the first thin film 12A is etched to form the first thin film pattern 12.
As described above, since the first thin film 12A is processed mainly by dry etching using a fluorine-based gas, the second thin film 13A is a material having resistance to dry etching using a fluorine-based gas. It is preferable that it is comprised from these.
Specific examples of the material constituting the second thin film 13A include chromium-based materials such as Cr, CrO, CrN, and CrNO, and tantalum-based materials such as Ta, TaO, TaN, and TaNO.
The second thin film 13A may have a single layer structure made of the same material or a multilayer structure made of two or more different materials.

The film thickness of the second thin film 13A only needs to have a thickness sufficient for an action as an etching mask when forming the first thin film pattern 12, but if the film is excessively thick, the second thin film pattern It becomes difficult to make 13 a fine pattern.
Therefore, although the film thickness of the second thin film 13A depends on the pattern size of the first thin film pattern 12, it is preferably in the range of about 3 nm to 50 nm.

  For the formation of the second thin film 13A, a conventionally known vacuum film forming method can be applied. For example, when the second thin film 13A is a chromium film (Cr), the reaction is performed in a argon gas atmosphere using a chromium target. It can be formed by sputtering.

<Second thin film pattern forming step>
Next, as shown in FIG. 2B, the second thin film 13 </ b> A is etched to form a second thin film pattern 13.
As a method for forming the second thin film pattern 13, a conventionally known method used in the production of a photomask, for example, a lithography technique by electron beam drawing can be suitably used.
As a method for etching the second thin film 13A, for example, when the second thin film 13A is made of a chromium-based material, a dry etching method using a mixed gas of a chlorine-based gas and an oxygen gas. In the case where the second thin film 13A is made of a tantalum material, a dry etching method using a chlorine gas can be used.

Here, in the example shown in FIG. 2B, the second thin film pattern 13 is three 1: 1 line-and-space patterns, and a defective defect portion 21 is generated in the central portion of the central line pattern. An example is shown.
In the example shown in FIG. 2B, in order to avoid complication, an example in which there is one defective defect portion is shown, but usually a plurality of defective defect portions often occur.

<Second thin film pattern defect inspection step>
Although not shown in order to avoid complication, in the present invention, after the formation process of the second thin film pattern 13 shown in FIG. 2B, the defect defect portion shown in FIG. Before the correction process 21, a defect inspection for detecting the defective defect portion 21 is performed.

Here, in the defect defect inspection of the conventional halftone type phase shift mask, the translucent mask pattern on the transparent substrate is inspected by transmitted light or reflected light.
On the other hand, in the present invention, the second thin film pattern 13 on the first thin film 12A is inspected. For example, when the first thin film 12A is a semi-transparent layer, the first thin film 12A is also conventional. In order to partially transmit the inspection light that has been used for the defect inspection, the difference between the transmittances of the first thin film 12A and the second thin film pattern 13 is used and an existing photomask defect inspection apparatus is used. The defect defect portion 21 of the second thin film pattern 13 can be detected.
Further, when the first thin film 12A is a light shielding film, an existing photomask defect inspection apparatus using reflected light and utilizing the difference in reflectance between the first thin film 12A and the second thin film pattern 13 Can be used to detect the defect 21 in the second thin film pattern 13.

<Second thin film pattern defect correcting step>
Next, the intermediate product obtained in the steps up to FIG. 2B is placed in the defect correcting apparatus, and the first deposition gas 31 is supplied as shown in FIGS. 2C and 2D. However, by irradiating the first electron beam 41, the correction material 51 is deposited on the defect defect portion 21 of the second thin film pattern 13 detected in the defect inspection step.

In the present invention, the first deposition gas 31 may be any material that can deposit a material having resistance to etching when the first thin film 12A is etched. A gas containing can be preferably used. Here, examples of the gas containing chromium (Cr) include a gas containing chromium hexacarbonyl (Cr (CO) ₆ ).

  In the present invention, the defect correcting apparatus used for correcting the defect defect portion described above corrects the defect defect of the conventional photomask by a partial deposition method using a deposition gas and an electron beam. Existing equipment can be used.

<First thin film pattern forming step>
After correcting all the defective defects detected as described above, the first thin film 12A exposed from the corrected second thin film pattern 13 is etched as shown in FIG. Then, the first thin film pattern 12 is formed, and then, as shown in FIG. 2F, the second thin film pattern 13 and the correction material 51 are removed to obtain the photomask 1.
Here, when the first thin film 12A is made of a material containing silicon (Si), a fluorine-based gas such as SF ₆ , CF ₄ , CHF ₃ , C ₂ F _6, or a mixed gas thereof is used. Alternatively, dry etching can be performed by using a gas in which oxygen is mixed with these gases as an etching gas to form a pattern.

  When the correction material 51 is made of the same material as the material forming the second thin film pattern 13, the correction material 51 is also removed in the process of removing the second thin film pattern 13, so the correction material There is no need to add a process for removing 51.

  As described above, in the photomask manufacturing method according to the present invention, the first thin film pattern 12 is formed before the step of forming the first thin film pattern 12 without using the conventional method of directly correcting the translucent mask pattern. When the thin film pattern 13 of 2 is formed, defect inspection is performed, the detected defective defect portion 21 is corrected, and the first thin film 12A is etched using the defect-corrected second thin film pattern 13 as an etching mask. Since the first thin film pattern 12 is formed, the defect defect can be corrected without being limited to the material constituting the first thin film pattern 12 (that is, the mask pattern), and a photomask having no defect defect is manufactured. can do.

<Drift correction>
In the present invention, the defect defect 21 can be corrected with high positional accuracy by correcting the drift of the first electron beam 41 during defect defect correction.

As described above, in the white defect correction process of the conventional halftone phase shift mask, the defect defect portion of the translucent mask pattern on the transparent substrate is mainly processed by partial deposition using a deposition gas and an electron beam. It was corrected by the method of position.
Here, insulating synthetic quartz glass is mainly used for the transparent substrate, and a compound containing molybdenum silicide (MoSi) having conductivity is mainly used for the translucent mask pattern. If the defect part is continuously irradiated with the electron beam, the defect defect part is charged and the electron beam drifts.
Therefore, in order to correct the defect defect portion of the translucent mask pattern with high positional accuracy, it is necessary to correct the electron beam drift while correcting the drift.

On the other hand, in the present invention, as shown in FIG. 2C, the defect defect portion 21 of the second thin film pattern 13 on the first thin film 12A is corrected by irradiation with the first electron beam 41. When the first thin film 12A is made of a conductive molybdenum silicide material, the defect defect portion 21 irradiated with the electron beam is in electrical contact with the conductive first thin film 12A. Therefore, charging is less likely to occur than in the prior art.
However, if there is a difference in conductivity between the material forming the first thin film 12A and the material forming the second thin film pattern 13 having the defective defect portion 21, charging occurs according to the difference.

  In the case where a thin film made of any one of silicon oxide (SiO), silicon nitride (SiN), and silicon oxynitride (SiON) that does not contain molybdenum (Mo) is used as the first thin film 12A, Since the thin film is insulative, if the defect defect portion is continuously irradiated with the electron beam, the defect defect portion may be charged and the electron beam may drift.

  Therefore, in the present invention, correcting the drift of the first electron beam 41 at the time of defect correction is advantageous in that correction can be performed with higher positional accuracy.

In the present invention, in order to correct the drift of the first electron beam 41 and correct the defect defect portion 21 with high positional accuracy, for example, the process shown in FIGS. 2C to 2F is changed. Thus, a method for manufacturing a photomask can be applied according to the steps shown in FIGS.
Also in this case, first, the second thin film pattern 13 is formed through the steps shown in FIGS. 2A to 2B, and defect inspection for detecting the defect defect portion 21 is performed.

  Next, the intermediate product obtained in the steps up to FIG. 2B is placed in the defect correcting apparatus, and the fourth deposition gas 32 is supplied while being supplied as shown in FIG. As shown in FIG. 3B, the deposit structure 61 is formed on the second thin film pattern 13 at a position different from the defect defect portion 21.

  Here, in the present invention, as will be described later, the deposit structure 61 does not remain in the finally obtained photomask 1. Therefore, the material constituting the deposit structure 61, that is, the material of the second deposition gas 32 can act as a mark for correcting the drift of the first electron beam 41. If it is a thing, it will not restrict | limit in particular and can be used.

For example, in the present invention, a gas containing chromium (Cr) or a gas containing silicon (Si) can be suitably used as the second deposition gas 32.
Here, the gas containing chromium (Cr) is a gas containing chromium hexacarbonyl (Cr (CO) ₆ ), and the gas containing silicon (Si) is tetraethyl orthosilicate (Si (OC ₂ H ₅ ) _4. ) Can be mentioned respectively.

  Next, as shown in FIG. 3C, the defect electron beam 41 is irradiated with the first electron beam 41 while the first deposition gas 31 is supplied, so that the result shown in FIG. As described above, the correction material 51 is deposited on the defect defect portion 21.

  Here, in order to prevent the defect defect portion 21 from being charged by continuously irradiating the first electron beam 41 and drifting the first electron beam 41 to deteriorate the position accuracy of defect correction, in advance, Using the deposited structure 61 thus formed as a positioning mark, the position is periodically corrected.

  After correcting all the defective defects detected as described above, as shown in FIG. 3E, the first thin film 12A exposed from the second thin film pattern 13 is etched, After forming the first thin film pattern 12, as shown in FIG. 3F, the second thin film pattern 13 and the deposit structure 61 are removed to obtain the photomask 1 according to the present invention.

  Here, in the white defect correction process of the conventional halftone phase shift mask, the deposit corresponding to the deposit structure 61 is formed on a translucent mask pattern at a position different from the defect defect portion. Usually, since it is not removed afterwards, there is a risk of causing foreign matter. Further, in order to remove the deposit corresponding to the deposit structure 61 described above, it is necessary to go through a step for the removal, which increases the number of steps and takes time for manufacturing, and increases the manufacturing cost. There was a bug.

On the other hand, in the present invention, the deposit structure 61 is formed on the second thin film pattern 13, and the second thin film pattern 13 is finally removed. The deposit structure 61 can also be removed in the step of removing the second thin film pattern 13.
Then, by removing the deposit structure 61, in the photomask 1 according to the present invention, it is possible to reduce the possibility of the generation of foreign matter compared to the related art.

(Second Embodiment)
Next, a second embodiment of the photomask manufacturing method according to the present invention will be described.

4 to 6 are explanatory views showing examples of defect defect forms and correction methods according to the present invention.
More specifically, the upper diagram in FIG. 4A is a schematic plan view in the vicinity of the defective defect portion 21 in the form of a pinhole, and the lower diagram is a cross-sectional view taken along the line AA in the upper diagram. 4B is a schematic plan view showing a state in which the correction material 51 is deposited on the defect defect portion 21 in FIG. 4A, and the lower view thereof is the upper view. It is BB sectional drawing.

  Similarly, the upper diagram in FIG. 5A is a schematic plan view of the vicinity of the defective defect portion 22 generated at the edge of the second thin film pattern 13, and the lower diagram is a CC diagram of the upper diagram. It is sectional drawing. 5B is a schematic plan view showing a state in which the correction material 51 is deposited on the defect defect portion 21 in FIG. 5A, and the lower diagram is a diagram of the upper diagram. It is DD sectional drawing.

  On the other hand, FIG. 6 is an explanatory diagram showing an example of a defect defect form and a correction method following FIG. Here, FIG. 6A is the same as FIG. 5A, and FIG. 6B is a schematic plan view showing a state in which excess correction material deposited around the defect defect portion 22 is removed by etching. The lower figure is an EE cross-sectional view of the upper figure.

  For example, as shown in FIG. 4 (a), when the defect defect portion 21 formed in the second thin film pattern 13 is a pinhole, it is deposited in the present invention as shown in FIG. 4 (b). The correction material 51 can be deposited so as to be larger than the defect defect portion 21 in both the vertical direction and the horizontal direction.

  As described above, when the form of the defect defect portion 21 is a pinhole, it is important to reliably fill the defect defect portion 21 with the correction material 51. Even if the correction material 51 is deposited so as to be large, the size of the correction material 51 usually does not affect the size of the first thin film pattern 12, and the correction material 51 is This is because the first thin film pattern 12 is removed together with the second thin film pattern 13.

  On the other hand, as shown in FIG. 5A, when the defect defect portion 22 is generated at the edge of the second thin film pattern 13, as shown in FIG. 5B, the defect defect portion 22 in the horizontal direction. If the correction material 51 is deposited so as to be larger than that, the correction material 51 protrudes beyond the edge position of the original second thin film pattern 13, and the excess portion of the correction material 51 causes the first correction material 51 to protrude. There arises a problem that the dimension of the thin film pattern 12 is not formed as designed.

More specifically, for example, as shown in FIG. 5A, when the horizontal size of the defect defect portion 22 in the CC cross section is L ₃ , as shown in FIG. The horizontal dimension of the correction material 51 in the D cross section is a size of L ₄ that is larger than L ₃ that is the size of the defect defect portion 21, and the edge position of the original second thin film pattern 13. In the case where the correction material 51 is deposited in a state where the surplus portion of the correction material 51 protrudes with a size of L ₅ , the first thin film 12A is formed by etching in this state. Also in the form of the first thin film pattern 12, the edge position of the portion corresponding to the DD cross section protrudes according to the size of L ₅ from the desired design position, and the dimension of the first thin film pattern 12 is It will not be formed as designed.
That is, the surplus portion of the correction material 51 becomes a residue defect portion in the first thin film pattern 12.

  For the above-described defects, for example, the first thin film pattern 12 is inspected for defects, and the detected residual defect portion is removed by a partial etching method using an etching gas and an electron beam as in the prior art. It is also possible.

However, when a thin film having high light resistance in the ArF excimer laser exposure as described above is used for the first thin film 12A, the conventional method for partial etching using an etching gas and an electron beam causes a residual defect portion. However, it has been found that the process of repairing residual defects cannot be completed in the same amount of time as before.
Further, in the first thin film pattern 12 formed from the thin film having high light resistance, the etching rate of the residual defect portion is not transparent in the conventional method by the partial etching correction method using the etching gas and the electron beam. It has also been found that the etching rate of the substrate becomes smaller and it is difficult to remove the residual defect portion without damaging the transparent substrate.

Note that, even if the first thin film 12A is a thin film having high light resistance in ArF excimer laser exposure, the first thin film pattern 12 is formed by dry etching using a fluorine-based gas as in the conventional case. Could be etched.
This is because dry etching with reactive ions excited by plasma has a stronger ability to etch the material constituting the first thin film 12A than partial etching with an etching gas and an electron beam in the process of correcting a residual defect. This is probably because of this.

  As a method for correcting the residual defect portion, there are a partial grinding method using an atomic force microscope (AFM) and a partial etching method using a focused ion beam. The former is a machine using an AFM probe. In order to remove the residual defect portion by mechanical grinding, it takes a long time to correct, and when the number of residual defects is large, it is not practical as a correction method. In addition, the latter is not preferable in that the ions used for correction remain in the material constituting the photomask, which may affect the phase shift effect, for example.

  Therefore, in this embodiment, after the correction material deposition step in the first embodiment, the surplus correction material deposited around the defect defect portion 22 of the second thin film pattern 13 is used for the first etching. Etching is performed by irradiating the second electron beam 42 while supplying the gas 71, and the first thin film 12 </ b> A exposed from the second thin film pattern 13 from which the excess correction material is removed is etched to obtain the first. The thin film pattern 12 is formed.

  More specifically, the photomask manufacturing method according to the present embodiment includes a transparent substrate, a first thin film formed on the transparent substrate, and a second thin film formed on the first thin film. A step of preparing a mask blank having: a step of etching the second thin film to form a second thin film pattern; and a defect inspection step of detecting a defective defect portion of the second thin film pattern; Correcting material deposition for depositing a correcting material on the defective defect portion of the second thin film pattern detected in the defect inspection step by irradiating the first electron beam while supplying the first deposition gas Irradiating the second electron beam while supplying the first etching gas to the surplus correction material deposited around the defect defect portion of the second thin film pattern by the step and the correction material deposition step Etched by And a step of removing the surplus correcting material, and a step of etching the first thin film exposed from the second thin film pattern from which the surplus correcting material is removed to form a first thin film pattern. is there.

Hereinafter, a second embodiment of the photomask manufacturing method according to the present invention will be described with reference to FIGS. Here, FIG. 7 and FIG. 8 are schematic process diagrams showing an example of the second embodiment of the photomask manufacturing method according to the present invention.
In addition, in order to avoid complication, the description which overlaps with the matter demonstrated in said 1st Embodiment is abbreviate | omitted suitably.

<Mask blanks preparation process>
As shown in FIG. 7A, in the present embodiment as well, as in the first embodiment, first, the transparent substrate 11, the first thin film 12A formed on the transparent substrate 11, and the first A mask blank having a second thin film 13A formed on one thin film 12A is prepared.

<Second thin film pattern forming step>
Next, as shown in FIG. 7B, the second thin film 13 </ b> A is etched to form a second thin film pattern 13.
Here, in the example shown in FIG. 7B, the second thin film pattern 13 is three 1: 1 line and space patterns, and the size of L ₃ is formed on the right edge of the center line pattern. The example which the defect defect part 22 of this has arisen is shown.

<Second thin film pattern defect inspection step>
Although not shown in order to avoid complication, the defect defect shown in FIG. 7C is also present in the present embodiment after the formation process of the second thin film pattern 13 shown in FIG. 7B. A defect inspection for detecting the defective defect portion 22 is performed before the correction process of the portion 22.

<Second thin film pattern defect correcting step>
[Correction material accumulation process]
Next, the intermediate product obtained in the steps up to FIG. 7B is placed in the defect correction apparatus, and the first deposition gas 31 is supplied as shown in FIGS. 7C and 7D. However, by irradiating the first electron beam 41, the correction material 51 is deposited on the defect defect portion 22 of the second thin film pattern 13 detected in the defect inspection step.
Here, as shown in FIG. 7 (d), the state of the correction member 51 when the deposition is finished, the excess portion of the modified material 51 than the edge position of the original second thin film pattern 13 size of L ₅ It was in a state of sticking out.

[Excess correction material removal process]
Next, in the present embodiment, as shown in FIGS. 8E and 8F, the above correction material is irradiated by irradiating the second electron beam 42 while supplying the first etching gas 71. The surplus portion 51 is removed by etching.

In the etching removal of the surplus portion of the correction material 51, vertical over-etching is allowed.
In the present embodiment, even if the portion of the first thin film 12A covered with the surplus portion of the correction material 51 is over-etched in the defect correction shown in FIG. Since it is a portion that is etched away in the subsequent formation process of the first thin film pattern 12 (FIG. 8G), as long as the overetching does not penetrate the first thin film 12A and reach the transparent substrate 11. No problem arises.
That is, the photomask manufacturing method according to the present embodiment also has an effect that the process margin in the surplus correcting material removing step is large.

In the present embodiment, when the first deposition gas 31 is a gas containing chromium (Cr), that is, when the correction material 51 is made of a material containing chromium (Cr), the first etching is performed. As the working gas 71, a gas containing fluorine (F) or a gas containing chlorine (Cl) can be used.
Here, examples of the gas containing fluorine (F) include a gas containing xenon fluoride (XeF ₂ ), and examples of the gas containing chlorine (Cl) include a gas containing nitrosyl chloride (NOCl). .

The first etching gas 71 is a gas containing fluorine (F) or a gas containing chlorine (Cl), oxygen (O ₂ ), water vapor (H ₂ O), nitrogen dioxide (NO ₂ ). ) Or ammonium carbonate ((NH ₄ ) ₂ CO ₃ ) is preferably a mixed gas to which one or two or more gases are added in order to achieve an etching promoting effect.

<First thin film pattern forming step>
After correcting all the defective defects detected as described above, the first thin film 12A exposed from the second thin film pattern 13 and the correction material 51 is removed as shown in FIG. Etching is performed to form the first thin film pattern 12, and then, as shown in FIG. 8H, the second thin film pattern 13 and the correction material 51 are removed to obtain the photomask 1.

  As described above, according to the present embodiment, in the second thin film pattern 13, the surplus correction material deposited around the defect defect portion 21 is supplied to the second electron beam while supplying the first etching gas. Then, the first thin film 12A is etched to form the first thin film pattern 12, so that the material constituting the first thin film pattern 12 (that is, the mask pattern) is limited. In addition, it is possible to correct a portion that may become a residue defect in the first thin film pattern 12, and it is possible to manufacture a photomask free from the residue defect due to the above-described excessive correction material.

<Drift correction>
Also in this embodiment, similarly to the first embodiment, the drift of the first electron beam 41 in the correction material deposition process is corrected, and the correction material 51 is applied to the defect defect portion 22 with high positional accuracy. It can also be deposited.
Similarly, it is also possible to correct the drift of the second electron beam 42 in the surplus correcting material removing step and to etch away the surplus correcting material with high positional accuracy.

FIG. 9 and FIG. 10 are schematic process diagrams showing an example of the process when the drift correction of each electron beam is performed in the present embodiment.
In the present embodiment, the drift of the first electron beam 41 in the correction material deposition process is corrected to deposit the correction material 51 on the defect defect portion 22 with high positional accuracy, and further, the second electrons in the surplus correction material removal process. In order to correct the drift of the line 42 and remove the excess correction material with high positional accuracy by etching, first, as shown in FIG. 9A, the fourth deposition gas 32 is supplied while the fourth deposition gas 32 is being supplied. By irradiating the electron beam 44, as shown in FIG. 9B, a deposit structure 61 is formed on the second thin film pattern 13 at a position different from the defect defect portion 22.

  Next, as shown in FIG. 9C, the first electron beam 41 is irradiated to the defect defect portion 22 while supplying the first deposition gas 31, and as shown in FIG. 9D. As described above, the correction material 51 is deposited on the defect defect portion 22.

  Here, in order to prevent the defect defect portion 22 from being charged by continuously irradiating the first electron beam 41 and drifting the first electron beam 41 to deteriorate the position accuracy of defect correction, in advance, Using the deposited structure 61 thus formed as a positioning mark, the position is periodically corrected.

  Next, as shown in FIG. 10E, by irradiating the second electron beam 42 while supplying the first etching gas 71, as shown in FIG. The excess portion is removed by etching.

  Here, in order to prevent the second electron beam 42 from drifting and the irradiation position accuracy from deteriorating by continuously irradiating the second electron beam 42, a deposit structure formed in advance. 61 is used as a positioning mark to periodically correct the position.

  After correcting all the defective defects detected as described above, the first thin film 12A exposed from the second thin film pattern 13 and the correction material 51 is etched as shown in FIG. The first thin film pattern 12 is formed by processing, and then the second thin film pattern 13, the correction material 51, and the deposit structure 61 are removed as shown in FIG. A photomask 1 according to the above is obtained.

(Third embodiment)
Next, a photomask manufacturing method according to a third embodiment of the present invention will be described.
As described above, the manufacturing process of the photomask including the phase shift mask includes many complicated processes, and the mask pattern is extremely fine. Residue defects, which are unnecessary surplus parts, are also likely to occur.

  FIG. 11 is an explanatory view showing a form example of a residue defect according to the present invention. More specifically, the upper diagram in FIG. 11 is a schematic plan view of the vicinity of the residual defect 81 generated at the edge of the second thin film pattern 13, and the lower diagram is a cross-sectional view taken along the line FF in the upper diagram. It is.

For example, as shown in FIG. 11, when a residual defect 81 is generated at the edge of the second thin film pattern 13, the first thin film 12 </ b> A formed when the first thin film 12 </ b> A is etched in this state. The shape of the first thin film pattern 12 also has a shape in which the edge position of the portion where the residual defect portion 81 exists protrudes in accordance with the size of L ₇ from the desired design position, and the dimension of the first thin film pattern 12 is designed. No longer formed on the street.
That is, there is a problem that the residue defect portion 81 of the second thin film pattern 13 causes a residue defect portion also in the first thin film pattern 12.

  For the above-described defects, for example, the first thin film pattern 12 is inspected for defects, and the detected residual defect portion is removed by a partial etching method using an etching gas and an electron beam as in the prior art. It is also possible.

However, as described in the second embodiment, when a thin film having high light resistance in ArF excimer laser exposure is used for the first thin film 12A, partial etching using a conventional etching gas and electron beam is used. In this correction method, there is a problem that etching of the residue defect portion does not proceed and the residue defect correction process cannot be completed in the same time as the conventional method.
Further, in the first thin film pattern 12 formed from the thin film having high light resistance, the etching rate of the residual defect portion is not transparent in the conventional method by the partial etching correction method using the etching gas and the electron beam. There is also a problem that the etching rate of the substrate becomes smaller and it is difficult to remove the residual defect portion without damaging the transparent substrate.

  As described in the second embodiment, as a method for correcting a residual defect portion, a partial grinding method using an atomic force microscope (AFM) and a partial etching method using a focused ion beam are also available. However, since the former removes the residual defect portion by mechanical grinding with an AFM probe, the correction takes a long time, and when the number of residual defects is large, it is not practical as a correction method. . In addition, the latter is not preferable in that the ions used for correction remain in the material constituting the photomask, which may affect the phase shift effect, for example.

  On the other hand, in the present invention, the residual defect portion generated in the second thin film pattern 13 can be removed by etching in the same manner as the surplus correcting material removing step described in the second embodiment.

  Therefore, in this embodiment, the defect defect portion and the residue defect portion of the second thin film pattern 13 are detected in advance, and in addition to the second embodiment, the second defect detected in the inspection step is detected. By irradiating the residual defect portion of the thin film pattern 13 with the third electron beam while supplying the second etching gas, the residual defect portion 81 of the second thin film pattern 13 is removed by etching. The first thin film pattern 12 is formed by etching the first thin film 12A exposed from the second thin film pattern 13 in which the portion and the residue defect portion are corrected.

  More specifically, the photomask manufacturing method according to the present embodiment includes a transparent substrate, a first thin film formed on the transparent substrate, and a second thin film formed on the first thin film. A step of preparing a mask blank having: a step of etching the second thin film to form a second thin film pattern; and detecting a defective defect portion and a residual defect portion of the second thin film pattern. A correction material is deposited on the defect defect portion of the second thin film pattern detected in the defect inspection step by irradiating the first electron beam while supplying the first deposition gas in the defect inspection step. And a second electron beam while supplying the first etching gas to the surplus correction material deposited around the defect defect portion of the second thin film pattern by the correction material deposition step. Irradiating By irradiating the third electron beam while supplying the second etching gas to the residual defect portion of the second thin film pattern detected in the inspection step and the surplus correction material removing step of removing the etching more A residual defect correcting step of etching away the residual defect portion of the second thin film pattern, and etching the first thin film exposed from the second thin film pattern from which the residual defect portion has been etched away to form a first Forming a thin film pattern.

Hereinafter, a third embodiment of the photomask manufacturing method according to the present invention will be described with reference to FIGS. Here, FIG. 12 and FIG. 13 are schematic process diagrams showing an example of the third embodiment of the photomask manufacturing method according to the present invention.
In addition, in order to avoid complication, the description which overlaps with the matter demonstrated in said 1st Embodiment and 2nd Embodiment is abbreviate | omitted suitably.

<Mask blanks preparation process>
As shown in FIG. 12A, in this embodiment as well, as in the second embodiment, first, the transparent substrate 11, the first thin film 12A formed on the transparent substrate 11, and the first A mask blank having a second thin film 13A formed on one thin film 12A is prepared.

<Second thin film pattern forming step>
Next, as shown in FIG. 12B, the second thin film 13 </ b> A is etched to form a second thin film pattern 13.
Here, in the example shown in FIG. 12B, the second thin film pattern 13 is three 1: 1 line and space patterns, and the size of L ₃ is formed on the right edge of the center line pattern. It has occurred the defect defect portion 22 and the right edge of the left side of the line pattern, an example in which the size of the residue defect portion 81 of the L ₇ has occurred.

<Second thin film pattern defect inspection step>
Although illustration is omitted to avoid complication, in this embodiment, the defect defect shown in FIG. 12C after the formation process of the second thin film pattern 13 shown in FIG. Before the repairing process of the part 22, a defect inspection for detecting the defect defect part 22 and the residual defect part 81 is performed.

<Second thin film pattern defect correcting step>
[Correction material accumulation process]
Next, the intermediate product obtained in the steps up to FIG. 12B is placed in the defect correcting apparatus, and the first deposition gas 31 is supplied as shown in FIGS. 12C and 12D. However, by irradiating the first electron beam 41, the correction material 51 is deposited on the defect defect portion 22 of the second thin film pattern 13 detected in the defect inspection step.
Here, as shown in FIG. 12 (d), the state of the correction member 51 when the deposition is finished, the excess portion of the modified material 51 than the edge position of the original second thin film pattern 13 size of L ₅ It was in a state of sticking out.

[Excess correction material removal process]
Next, as shown in FIG. 12E and FIG. 13F, the surplus portion of the correction material 51 is irradiated by irradiating the second electron beam 42 while supplying the first etching gas 71. (Horizontal size L ₅ ) is removed by etching.

[Residue defect correction process]
Further, in the present embodiment, as shown in FIGS. 13G and 13H, the residual defect portion 81 (by irradiation with the third electron beam 43 while supplying the second etching gas 72). The horizontal size L ₇ ) is removed by etching.

In etching removal of the residual defect portion 81, vertical over-etching is allowed.
In the conventional black defect correction process of the halftone phase shift mask, the semitransparent mask pattern on the transparent substrate is partially etched away. Therefore, if the transparent substrate is etched by vertical over-etching, the phase shift effect at that portion may become non-uniform with other portions.

On the other hand, in the present embodiment, the portion of the first thin film 12A covered with the residue defect portion 81 is overetched in the defect correction shown in FIG. Since it is a portion that is etched away in the subsequent formation process of the first thin film pattern 12 (FIG. 13I), as long as the overetching does not penetrate the first thin film 12A and reach the transparent substrate 11. No problem arises.
That is, the photomask manufacturing method according to the present embodiment also has an effect that the process margin in the black defect correction process is large.

)
In the present embodiment, when the second thin film pattern 13 is made of a material containing chromium (Cr), the second etching gas 72 includes a gas containing fluorine (F) or chlorine (Cl). A gas containing can be used.
Here, examples of the gas containing fluorine (F) include a gas containing xenon fluoride (XeF ₂ ), and examples of the gas containing chlorine (Cl) include a gas containing nitrosyl chloride (NOCl). .

In addition, the second etching gas 72 is formed by adding oxygen (O ₂ ), water vapor (H ₂ O), nitrogen dioxide (NO ₂ ) to the gas containing fluorine (F) or the gas containing chlorine (Cl). ) Or ammonium carbonate ((NH ₄ ) ₂ CO ₃ ) is preferably a mixed gas to which one or two or more gases are added in order to achieve an etching promoting effect.

<First thin film pattern forming step>
After correcting all the detected defect portions and residual defect portions as described above, the first exposed from the second thin film pattern 13 and the correction material 51 as shown in FIG. The thin film 12A is etched to form the first thin film pattern 12, and then the second thin film pattern 13 and the correction material 51 are removed to obtain the photomask 1 as shown in FIG. 13 (j). .

  As described above, in the photomask manufacturing method according to the present embodiment, without using the conventional method of directly correcting the translucent mask pattern, before the step of forming the first thin film pattern 12, When the second thin film pattern 13 is formed, defect inspection is performed, the detected defective defect portion 22 and the residual defect portion 81 are corrected, and the first thin film 12A is etched using the defect corrected second thin film pattern 13 Since the first thin film pattern 12 is formed by processing, the defect defect and the residual defect can be corrected without being limited to the material constituting the first thin film pattern 12 (that is, the mask pattern). A photomask free from residue defects can be manufactured.

  In the example shown in FIG. 12 and FIG. 13, the example of the process of correcting the defect is shown in the order of the correction material deposition process, the surplus correction material removal process, and the residual defect correction process, but in this embodiment, the correction material deposition process. The surplus correction material removal process may be followed after the process, and for example, a defect correction process, a correction material accumulation process, and a surplus correction material removal process may be performed in this order.

<Drift correction>
Also in this embodiment, similarly to the first embodiment, the drift of the first electron beam 41 in the correction material deposition process is corrected, and the correction material 51 is applied to the defect defect portion 22 with high positional accuracy. It can also be deposited.
Further, similarly to the second embodiment described above, it is possible to correct the drift of the second electron beam 42 in the surplus correcting material removing step and to etch away the surplus correcting material with high positional accuracy.

Furthermore, it is possible to correct the drift of the third electron beam 43 in the residue defect correcting step and to remove the residue defect portion 81 with high positional accuracy by etching.
More specifically, the second thin film pattern at a position different from the residue defect portion 81 is obtained by irradiating the fourth electron beam 44 while supplying the second deposition gas 32 in the residue defect correction step. 13, the deposit structure 61 formed on the substrate 13 is used as a positioning mark, the position where the third electron beam 43 is irradiated is corrected, and the residual defect portion 81 of the second thin film pattern is removed by etching. You can also.

  In addition, about the method of correct | amending the drift of the 3rd electron beam 43 in said residue defect correction process, in the surplus correction material removal process in said 2nd Embodiment with reference to said FIG.9 and FIG.10. Since it can be explained in the same manner as the method of correcting the drift of the second electron beam 42, illustration is omitted.

(Phase shift mask)
Next, the form of the phase shift mask obtained by the photomask manufacturing method according to the present invention will be described.
FIG. 14 is a schematic cross-sectional view showing a configuration example of a phase shift mask according to the present invention.
Here, FIG. 14A shows a form in which the second thin film 13A also serves as the light shielding layer 102, and FIG. 14B shows the light shielding layer 102 composed of two layers, the second thin film 13A and the light shielding material 101. Each form is shown.

In general, the halftone phase shift mask has a light shielding layer in an area outside the mask pattern area.
When the area outside the mask pattern area is also composed only of a semitransparent layer (mainly 6% transmittance) with respect to the ArF excimer laser, the ArF excimer laser that transmits the area outside the mask pattern area is used. In order to prevent such a problem that the energy overlaps and the resist on the wafer is exposed to light, the above-described light shielding layer is provided.
In the present invention, when the second thin film 13A has a sufficient light shielding property against the ArF excimer laser, the second thin film 13A can also serve as the light shielding layer 102.

  For example, in the phase shift mask 1a shown in FIG. 14A, the light shielding layer 102 is provided in the light shielding area 92 outside the mask pattern area 91. The thin film 13A can be the same as that formed on the first thin film 12A. In other words, the light shielding layer 102 of the phase shift mask 1a can also be used as the second thin film 13A of the present invention.

  More specifically, the second thin film 13 </ b> A formed in the mask pattern region 91 is processed into the second thin film pattern 13 and finally removed, but the second thin film formed in the light shielding region 92. 13A is left as it is and acts as the light shielding layer 102 in the phase shift mask 1a.

  In the present invention, as described above, since the second thin film 13A also serves as the light shielding layer 102, it is not necessary to separately form the light shielding layer 102, the number of steps can be reduced, and the manufacturing cost can be reduced. Can be reduced.

Further, in the present invention, the light shielding layer 102 may be configured by two layers of the second thin film 13A and the light shielding material 101 as in the phase shift mask 1b shown in FIG.
In this case, the light shielding property as the light shielding layer 102 is mainly borne by the light shielding material 101, and thus the second thin film 13A has a greater degree of freedom with respect to material selection and film thickness.
In particular, in order to achieve miniaturization of the semitransparent mask pattern, it is necessary to reduce the thickness of the second thin film 13A. For the purpose of forming a finer semitransparent mask pattern, as in the phase shift mask 1b, A configuration in which the light shielding layer 102 is constituted by two layers of the second thin film 13A and the light shielding material 101 is useful.

14A and 14B, the second thin film 13A may have a single layer structure made of the same material, or may be made of two or more different materials. It may be a multilayer structure.
In the form shown in FIG. 14B, the light shielding material 101 may have a single layer structure made of the same material or a multilayer structure made of two or more different materials.

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

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

Example 1
A 6-inch square and 0.25-inch thick synthetic quartz glass substrate optically polished is used as the transparent substrate 11, and the atomic ratio of Mo: Si: O: N is 3: 44: 1: 54 as the first thin film 12A. A mask blank was prepared in which a molybdenum silicide oxynitride film (MoSiON) having a thickness of 60 nm was formed, and a chromium film (Cr) having a thickness of 46 nm was formed as the second thin film 13A.

  Next, an electron beam resist was applied on the chromium film (Cr), and pattern drawing and development were performed with an electron beam drawing apparatus to form a resist pattern.

  Next, the chromium film exposed from the resist pattern is dry-etched with a mixed gas of chlorine and oxygen to form a chromium film pattern as the second thin film pattern 13, and then the resist pattern is removed by ashing with oxygen plasma, After cleaning, the chromium film pattern of the obtained intermediate product was inspected using a defect inspection apparatus (MATRICS X700 manufactured by Lasertec Corporation).

Next, the intermediate product is placed in a defect correction device (MeRiT manufactured by Carl Zeiss), and the fourth electron is supplied while supplying chromium hexacarbonyl (Cr (CO) ₆ ) gas as the second deposition gas 32. By irradiating the line 44, a deposit structure having a diameter of approximately 30 nm was formed on the chromium film pattern at a position different from the defect defect portion and the residue defect portion detected by the above inspection.

Next, by supplying the first electron beam 41 while supplying chromium hexacarbonyl (Cr (CO) ₆ ) gas as the first deposition gas 31, the defect defect portion detected by the above inspection is applied. Correction material 51 was deposited.
In this correction material deposition step, the position of the first electron beam 41 is prevented from drifting by periodically correcting the position using the deposit structure as a positioning mark.

Next, the edge of the chromium film pattern is irradiated by irradiating the second electron beam 42 while supplying a mixed gas of xenon fluoride (XeF ₂ ) and water vapor (H ₂ O) as the first etching gas 71. The surplus portion of the correction material 51 was removed by etching.
In this surplus correcting material removing step, the reference pattern in the die-to-die inspection was referred to correct the pattern so as to have the same shape. In addition, the position of the second electron beam 42 is prevented from drifting by periodically correcting the position using the deposit structure as a positioning mark.
The die-to-die inspection may be a die-to-database inspection, but the die-to-die inspection is preferable because it can realize high accuracy.

Next, detection is performed in the above inspection by irradiating the third electron beam 43 while supplying a mixed gas of xenon fluoride (XeF ₂ ) and water vapor (H ₂ O) as the second etching gas 72. The residual defect portion was removed by etching.
In this residue defect correction process, the position of the deposit structure is periodically used for positioning marks to prevent the third electron beam 43 from drifting.

After correcting all the defective defects and residual defects detected as described above, the molybdenum silicide oxynitride film exposed from the chromium film pattern is dry-etched with SF ₆ gas to produce a translucent mask pattern Then, the chromium film pattern and the correction material 51 were removed with a mixed gas of chlorine and oxygen, and the photomask of Example 1 was obtained. The results are shown in Table 1.

(Example 2)
Example 1 is the same as Example 1 except that a molybdenum silicide oxynitride film (MoSiON) having a film thickness of 63 nm with an Mo: Si: O: N atomic ratio of 4: 42: 6: 46 is used as the first thin film 12A. Similarly, the photomask of Example 2 was obtained. The results are shown in Table 1.

(Example 3)
Example 1 is the same as Example 1 except that a 45 nm-thickness silicon oxide film (SiO) having an Mo: Si: O: N atomic ratio of 0: 81: 18: 0 is used as the first thin film 12A. Thus, a photomask of Example 3 was obtained. The results are shown in Table 1.

Example 4
Example 1 except that a silicon oxynitride film (SiON) having a film thickness of 63.5 nm with an atomic ratio of Mo: Si: O: N of 0: 45: 10: 45 was used as the first thin film 12A. In the same manner as described above, the photomask of Example 4 was obtained. The results are shown in Table 1.

(Example 5)
Example 1 is the same as Example 1 except that a 57 nm-thickness silicon nitride film (SiN) having an Mo: Si: O: N atomic ratio of 0: 42: 0: 58 is used as the first thin film 12A. Thus, a photomask of Example 5 was obtained. The results are shown in Table 1.

(Comparative Example 1)
Example 1 is the same as Example 1 except that a molybdenum silicide oxynitride film (MoSiON) having a film thickness of 68 nm with a Mo: Si: O: N atomic ratio of 6: 37: 3: 54 is used as the first thin film 12A. Mask blanks having the same configuration were prepared.

Using this mask blank, a chromium film pattern was formed in the same manner as in Example 1. In Comparative Example 1, unlike the first to fourth embodiments, the resist pattern is not removed. After the chromium film pattern is formed, the molybdenum silicide oxynitride film exposed from the resist pattern and the chromium film pattern ( Mo: Si: O: N = 6: 37: 3: 54) was dry-etched with SF ₆ gas to form a first thin film pattern.
Thereafter, the resist pattern was removed by ashing with oxygen plasma, and then the chromium film pattern was removed with a mixed gas of chlorine and oxygen to obtain a photomass of Comparative Example 1.

  The first thin film pattern of the photomask of Comparative Example 1 obtained as described above was inspected using a defect inspection apparatus (MATRICS X700 manufactured by Lasertec Corporation).

Next, the photomask of Comparative Example 1 is placed in a defect correction apparatus (MeRiT manufactured by Carl Zeiss), and a mixed gas of xenon fluoride (XeF ₂ ) and water vapor (H ₂ O) is supplied as an etching gas. The residue defect portion detected in the above inspection was irradiated with an electron beam to attempt etching removal of the residue defect portion.
The residual defect portion of the first thin film pattern of Comparative Example 1 could be removed by etching under the above conditions, and all detected residual defect portions could be corrected.
On the other hand, the defect defect portion detected by the above inspection was not corrected because there was no deposition gas capable of depositing molybdenum silicide (MoSi).
The results are shown in Table 1.

(Comparative Example 2)
Except for using a molybdenum silicide oxynitride film (MoSiON) in which the atomic ratio of Mo: Si: O: N is 7: 37: 6: 45 as the first thin film 12A, the same as in Comparative Example 1, A photomask of Comparative Example 2 was obtained.
Similar to Comparative Example 1, the residual defect portion of the first thin film pattern of Comparative Example 2 could be removed by etching, and all the detected residual defect portions could be corrected.
On the other hand, the defect defect portion detected by the above inspection was not corrected because there was no deposition gas capable of depositing molybdenum silicide (MoSi).
The results are shown in Table 1.

(Evaluation)
The atomic percentage of each atom constituting the first thin film of Examples 1 to 5 and Comparative Examples 1 and 2, and the atomic ratio of molybdenum (Mo) to silicon (Si) in the first thin film (A _Mo / A _Si), etching selectivity of the transparent substrate in the residue defect correction of the first thin film finally obtained quality defect repair in the photomask, the durability against ArF excimer laser exposure, shown in Table 1.
Note that the atomic percentage of each atom constituting the first thin film was determined by XPS analysis.

As shown in Table 1, in Comparative Example 1 and Comparative Example 2, the selection ratio with the underlying transparent substrate (synthetic quartz glass) was changed by a conventional partial etching correction method using an etching gas and an electron beam. With a value of 2 or more, the residual defect portion of the first thin film could be easily corrected directly.
However, since there is no deposition gas capable of depositing molybdenum silicide (MoSi) for defect defects, there is no effective means for directly correcting the defect defect portion of the first thin film.
Moreover, the light resistance with respect to ArF excimer laser exposure of the 1st thin film pattern in the obtained photomask was inadequate.

On the other hand, as shown in Table 1, the atomic ratio (A _Mo / A _Si ) between molybdenum (Mo) and silicon (Si) in the first thin film satisfies the relationship 0 ≦ A _Mo / A _Si ≦ 1/10. In the first thin films of Examples 1 to 5, in the conventional partial etching correction method using an etching gas and an electron beam, etching of the residual defect portion of the first thin film does not proceed, and The selectivity with respect to the transparent substrate (synthetic quartz glass) is a value of 0.25 or less, and it is difficult to directly correct the residual defect portion of the first thin film.

However, by using the above-described method for manufacturing a photomask according to the present invention, a photomask having no defect defect portion and no residue defect portion even in the configuration having the first thin film having the composition shown in Examples 1 to 5 Could get.
Moreover, the light resistance with respect to ArF excimer laser exposure of the 1st thin film pattern in the photomask obtained by Examples 1-5 was sufficient.

  As described above, in the present invention, even if the photomask has a pattern composed of a thin film having high light resistance to ArF excimer laser exposure, the defect defect and the residue defect can be corrected. It was confirmed that it was possible to produce a photomask without any defects.

DESCRIPTION OF SYMBOLS 1 ... Photomask 1a, 1b ... Phase shift mask 11 ... Transparent substrate 12 ... 1st thin film pattern 12A ... 1st thin film 13 ... 2nd thin film pattern 13A ... Second thin film 21, 22: Defect defect 31 ... First deposition gas 32 ... Second deposition gas 41 ... First electron beam 42 ... First Second electron beam 43 ... Third electron beam 44 ... Fourth electron beam 51 ... Correction material 61 ... Deposit structure 71 ... First etching gas 72 ... Second etching gas 81... Residue defect portion 91... Mask pattern region 92 .. light shielding region 101 .. light shielding material 102.

Claims (15)

Preparing a mask blank having a transparent substrate, a first thin film formed on the transparent substrate, and a second thin film formed on the first thin film;
Etching the second thin film to form a second thin film pattern;
A defect inspection step of detecting a defective defect portion of the second thin film pattern;
A correction material deposition step of depositing a correction material on the defect defect portion of the second thin film pattern detected in the defect inspection step by irradiating the first electron beam while supplying the first deposition gas. When,
Etching the first thin film exposed from the second thin film pattern on which the correction material is deposited to form a first thin film pattern;
A method for manufacturing a photomask, comprising: Preparing a mask blank having a transparent substrate, a first thin film formed on the transparent substrate, and a second thin film formed on the first thin film;
Etching the second thin film to form a second thin film pattern;
A defect inspection step of detecting a defective defect portion of the second thin film pattern;
A correction material deposition step of depositing a correction material on the defect defect portion of the second thin film pattern detected in the defect inspection step by irradiating the first electron beam while supplying the first deposition gas. When,
Etching removal of the excess correction material deposited around the defect defect portion of the second thin film pattern by irradiating the second electron beam while supplying the first etching gas in the correction material deposition step. A surplus correction material removing step to perform,
Etching the first thin film exposed from the second thin film pattern from which the excess correction material has been removed to form a first thin film pattern;
A method for manufacturing a photomask, comprising: Preparing a mask blank having a transparent substrate, a first thin film formed on the transparent substrate, and a second thin film formed on the first thin film;
Etching the second thin film to form a second thin film pattern;
A defect inspection step of detecting a defect defect portion and a residue defect portion of the second thin film pattern;
A correction material deposition step of depositing a correction material on the defect defect portion of the second thin film pattern detected in the defect inspection step by irradiating the first electron beam while supplying the first deposition gas. When,
Etching removal of the excess correction material deposited around the defect defect portion of the second thin film pattern by irradiating the second electron beam while supplying the first etching gas in the correction material deposition step. A surplus correction material removing step to perform,
Residual defects of the second thin film pattern are irradiated by irradiating a third electron beam to the residual defect portions of the second thin film pattern detected in the defect inspection step while supplying a second etching gas. A residue defect correcting step for etching and removing the part,
Etching the first thin film exposed from the second thin film pattern from which the residual defect has been removed by etching to form a first thin film pattern;
A method for manufacturing a photomask, comprising: In the correction material deposition step,
A positioning mark is formed on the deposit structure formed on the second thin film pattern at a position different from the defect defect portion by irradiating the fourth electron beam while supplying the second deposition gas. 4. The correction material is deposited on the defective defect portion of the second thin film pattern by correcting the position where the first electron beam is irradiated. 5. The method for producing a photomask according to one item. In the surplus correcting material removing step,
By irradiating the fourth electron beam while supplying the second deposition gas, the deposit structure formed on the second thin film pattern at a position different from the defect defect portion is used for positioning. The surplus correction material deposited around the defect defect portion of the second thin film pattern is corrected by using the mark to correct the position where the second electron beam is irradiated, and is removed by etching. The manufacturing method of the photomask as described in any one of Claim 2 thru | or 4. In the residual defect correction step,
By irradiating the fourth electron beam while supplying the second deposition gas, the deposit structure formed on the second thin film pattern at a position different from the residue defect portion is used for positioning. 6. The residual defect portion of the second thin film pattern is removed by etching by correcting the position of irradiation with the third electron beam, which is used for a mark. 6. The manufacturing method of the photomask of claim | item. The atomic ratio (A _Mo / A _Si ) of molybdenum (Mo) and silicon (Si) in the first thin film satisfies a relationship of 0 ≦ A _Mo / A _Si ≦ 1/10. The manufacturing method of the photomask as described in any one of Claims 6 thru | or 6.   The first thin film comprises one or more of a silicon oxide film (SiO), a silicon nitride film (SiN), and a silicon oxynitride film (SiON). The method for producing a photomask according to claim 6.   9. The second thin film is made of a material containing chromium (Cr), and the first deposition gas is a gas containing chromium (Cr). The manufacturing method of the photomask as described in any one of these. The photomask manufacturing method according to claim 9, wherein the gas containing chromium (Cr) is a gas containing chromium hexacarbonyl (Cr (CO) ₆ ).   The first etching gas and the second etching gas are gases containing fluorine (F) or gases containing chlorine (Cl), respectively. Photomask manufacturing method. The gas containing fluorine (F) is a gas containing xenon fluoride (XeF ₂ ), and the gas containing chlorine (Cl) is a gas containing nitrosyl chloride (NOCl). The manufacturing method of the photomask as described. The first etching gas and the second etching gas are any of oxygen (O ₂ ), water vapor (H ₂ O), nitrogen dioxide (NO ₂ ), and ammonium carbonate ((NH ₄ ) ₂ CO ₃ ). 13. The photomask manufacturing method according to claim 11 or 12, wherein the mixed gas is a mixed gas to which one or two or more gases are added.   The photo according to any one of claims 4 to 13, wherein the second deposition gas is a gas containing chromium (Cr) or a gas containing silicon (Si). Mask manufacturing method. The gas containing chromium (Cr) is a gas containing chromium hexacarbonyl (Cr (CO) ₆ ), and the gas containing silicon (Si) is a gas containing tetraethyl orthosilicate (Si (OC ₂ H ₅ ) ₄ ). The method of manufacturing a photomask according to claim 14, wherein:

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