KR20060058467A - Repair method of deffect for photomask - Google Patents

Abstract

      The present invention relates to a photomask, and more particularly, to a photomask defect correction method for manufacturing a photomask free of defects by correcting a defect generated during a photomask manufacturing process.

This method includes providing a photomask including a back defect in which a predetermined region of a mask pattern is lost, a back defect correction step of depositing a compensation layer on a lost region of the mask pattern, and a phase error correction step of the compensation layer for the mask pattern. Include.

       Photomask, White Defect, Black Defect, Defect Fix, FIB

Description

REPAIR METHOD OF DEFFECT FOR PHOTOMASK}             

1 is a view schematically showing a bag defect formed in a photomask.

2 is a photograph showing an example of a back defect formed in a photomask.

3 is a view showing a photomask modified by the conventional defect correction method.

4 is a view schematically showing a black defect formed in the photomask.

5 is a view showing a photomask modified by the conventional black defect correction method.

6 is a photograph showing an example of photomas modified by the conventional black defect correction method.

7 is a view showing a photomask modified by the method for correcting a bag defect of the present invention.

FIG. 8 is a cross-sectional view of the photomask of FIG. 7 taken along the line 'VIII'.

9 is a view showing a photomask modified by the black defect correction method of the present invention.

FIG. 10 is a cross-sectional view of the photomask of FIG. 9 taken along the line VIII-VIII. FIG.

       Explanation of symbols on main parts of drawing

       100: transparent substrate 150: mask pattern

       200: back defect 300: compensation film

400: trench 500: black defect

       The present invention relates to a photomask, and more particularly, to a photomask defect correction method for manufacturing a photomask free of defects by correcting a defect generated during a photomask manufacturing process.

       BACKGROUND OF THE INVENTION Semiconductor integrated circuit manufacturing processes generally include a number of photographic processes that are performed to form circuit elements on the surface of a semiconductor substrate. In particular, in order to form a highly integrated circuit with a reliable photo process, the photomask must be able to define a fine pattern, and defects in the photomask are required to improve mask production yield and shorten turn around time (TAT). It should be formed without.

      When fabricating a photomask, if particles or etch residues are present on the mask in the manufacturing process step, defects occur because the site with the particles or residues is not exposed in the exposing step.

    Such defects in the photomask are largely clear defects and black defects.

       The back defect is a phenomenon in which a part of the pattern is lost due to a process error such as an etching error during the process of forming the mask pattern on the transparent substrate, and the black defect is an unnecessary transparent substrate without the mask pattern forming material forming the pattern. It is a phenomenon remaining on the stomach.

       Hereinafter, problems with the conventional photomask will be described in detail with reference to the accompanying drawings.

       First, the bag defect will be described with reference to FIGS. 1 to 3.

      1 is a view schematically showing a bag defect formed on a photomask, and FIG. 2 is a photograph showing an example of a bag defect formed on a photomask.

      First, a mask pattern forming material (not shown) is deposited on the transparent substrate 100 and patterned to form a plurality of mask patterns 150 on the substrate 100. The mask pattern 150 may be formed of molybdenum (Mo) or molybdenum silicide nitride (MoSiN) having a transmittance of 6%.

       At this time, as shown in FIG. 1, a predetermined region of the mask pattern 150 is lost, so that a back defect 200 in which a part of the substrate is exposed is generated.

       Here, '(A)' of FIG. 1 is a cross-sectional view of the photomask shown in '(B)' of FIG. 1 taken along a line A-A '.

       In order to correct such a back defect, the compensation film was deposited on the back defect part conventionally.                         

       Next, a method for correcting a conventional back defect will be described below with reference to FIG. 3.

      3 is a view showing a photomask modified by a conventional bag defect correction method.

      As shown in FIG. 3, a compensation region 300 is deposited by irradiating a focused ion beam (FIB) to a back defect 200 in which a predetermined region of the mask pattern 150 is lost and the substrate 100 is exposed. The back defect 200 was corrected.

      Here, '(A)' in FIG. 3 is a cross-sectional view of the photomask shown in '(B)' in FIG. 3 by cutting the line A-A '.

      However, when the compensation film 300 is deposited on the back defect 200, different transmittances of the compensation film 300 and the mask pattern 150, for example, the compensation film 300 have a transmittance of 0% as the stylene film. Since the mask pattern 150 has a 6% transmittance of chromium (Cr) or the like, a phase error of the compensation layer 300 with respect to the mask pattern 150 occurs. As such, when a phase error occurs, the accuracy of the depth of focus of the photomask is lowered.

      In the above, the white defect has been described. Hereinafter, the black defect will be described with reference to FIGS. 4 to 6.

       4 is a view schematically showing a black defect formed in the photomask.

      First, a mask pattern forming material (not shown) is deposited on the transparent substrate 100 and patterned to form a plurality of mask patterns 150 on the substrate 100. The mask pattern 150 may define a light transmitting part on the substrate 100, and may be formed of molybdenum (Mo) or molybdenum silicide nitride (MoSiN) having a transmittance of 6%.

      At this time, as shown in FIG. 4, the black defect 500 in which the mask pattern forming material is left unnecessarily is formed.

      Here, '(A)' of FIG. 4 is a cross-sectional view of the photomask shown in '(B)' of FIG. 4 taken along a line A-A '.

      Accordingly, the black defect is conventionally corrected by removing the mask pattern forming material remaining on the substrate of the light transmitting portion.

      Then, the conventional black defect correction method will be described below with reference to FIGS. 5 and 6.

      5 is a view showing a photomask modified by the conventional black defect correction method, Figure 6 is a photograph showing an example of a photomask modified by the conventional black defect correction method.

      As shown in FIG. 5, in the related art, the black defect 500 is corrected by irradiating an FIB (Focused Ion Beam) on an unnecessary mask pattern forming material remaining on the substrate of the light transmitting part to remove the mask pattern forming material.

      Here, '(A)' of FIG. 5 is a cross-sectional view of the photomask shown in '(B)' of FIG. 5 taken along line A-A '.

However, when the black defect 500 is removed, the predetermined region of the substrate of the light transmitting portion where the black defect 500 is present is lost as shown in 'C' of FIG. 6, and thus the light transmitting portion adjacent to the substrate of the light transmitting portion is lost. A step will occur. Therefore, a phase error is generated due to the step, which affects the mask pattern and lowers the accuracy of the depth of focus of the photomask.

The present invention is to solve the above problems, and relates to a photomask defect correction method for manufacturing a photomask without a defect by correcting a defect generated during the photomask manufacturing process.

       According to an aspect of the present invention, there is provided a photomask including a back defect in which a predetermined region of a mask pattern is lost, a step of correcting a back defect in which a compensation film is deposited on a lost region of the mask pattern, and A method of correcting a defect of a photomask including a phase error correction step of the compensation layer with respect to a mask pattern is provided. Here, in the phase error correcting step, it is preferable to form a trench having a predetermined width and a predetermined depth along one side of the compensation layer not in contact with the mask pattern.

       In addition, the width and depth of the trench may be adjusted according to the phase error of the mask pattern and the compensation layer.

       According to another aspect of the present invention, there is provided a photomask including a black defect in which a mask pattern forming material remains on a transparent substrate, and a black mask removing the mask pattern forming material remaining on the substrate. A defect correction method of a photomask includes a defect correction step and a phase error correction step due to a difference in transmittance between a mask pattern and a substrate damaged by a portion of the black defect.

       Here, in the phase error correction step, it is preferable to form a trench having a predetermined width and depth along one side of the black defect adjacent to the mask pattern.

In addition, the trench width and depth may be adjusted according to the phase error of the substrate where some regions are damaged due to mask pattern and black defect removal.

       Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement the present invention.

      In the drawings, the thickness of layers, films, panels, regions, etc., are exaggerated for clarity. Like parts are designated by like reference numerals throughout the specification.

      Now, a defect correction method of a photomask according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

      First, a defect correction method of the photomask according to the first embodiment of the present invention will be described in detail with reference to FIGS. 7 and 8 and FIGS. 1 to 3. Here, the photomask applied to the first embodiment is a phase inversion mask in which a back defect is generated.

    As shown in FIG. 1, a predetermined region of the mask pattern 150 is lost and a portion of the substrate 100 is exposed to the back defect 200, which is conventionally compensated as shown in FIG. 3 by using a focused ion beam (FIB). The back defect 200 was compensated for by depositing the film 300. However, when the compensation film 300 is deposited on the back defect 200, different transmittances of the compensation film 300 and the mask pattern 150, for example, the compensation film 300 of the present invention have a transmittance of 0%. Since the mask pattern 150 is made of molybdenum (Mo) or molybdenum silicide nitride (MoSiN) having a transmittance of 6%, the compensation film 300 for the mask pattern 150 is formed. Phase error occurs.

      Accordingly, in the present invention, a trench is formed to correct the above-described problem, thereby correcting a phase error with respect to the compensation layer.

       Next, a method of correcting a phase error caused by a compensation film according to an embodiment of the present invention will be described in detail with reference to FIGS. 7 and 8.

       7 and 8 illustrate a photomask modified by the method for correcting a back defect of the present invention.

       First, as shown in FIG. 7, a compensation pattern 300 is not adjacent to the mask pattern 150 as shown in 'D' of FIG. 7 by using a focused ion beam (FIB) in the mask pattern 150 on which the compensation film 300 is deposited. A trench 400 having a predetermined width and depth is formed along one side of the film 300.

       8 is a cross-sectional view of the photomask shown in FIG. 7 taken along the line VIII-VIII.

       In particular, the width and depth of the trench 400 are formed in consideration of a phase error due to a difference in transmittance between the compensation layer 300 and the mask pattern 150 adjacent to the compensation layer 300.

       Next, embodiments of the present invention will be described in detail. The embodiment of the present invention proceeds under the assumption that the phase error is 180 degrees.

       First, the formation width of the trench 400 is fixed to 100 kW and the trench 400 is formed to a depth of up to 2400 kW when using Arf, and up to 1900 kW when using Krf.

       Next, in the case of Arf, an exposure process is performed on the photomask having the trench 400 formed to have a depth of 2400 Hz and a width of 100 Hz to determine whether the 180 ° phase error is corrected and returned to normal. In this case, if the phase error is not corrected, the width of both sides of the trench 400 of 100 ms is repeatedly etched by 10 ms to find a point where the error of 180 ° is resolved. Also in the case of Krf, when the 180 ° phase error of the photomask having the trench 400 formed to a depth of 1900 와 and a width of 100 가 is corrected and does not return to qualitatively, the widths of both sides of the trench 400 are changed as described above. Repeatedly add and etch by 10Å to find the point where the error of 180 ° is solved.

      When the phase error correction step is performed as described above, the phase error of the mask pattern 150 adjacent to the compensation layer 300 is corrected due to the trench 400 to correct the back defect.

      Now, a method of correcting a defect of a photomask according to a second embodiment of the present invention will be described in detail with reference to FIGS. 9 and 10 and FIGS. 4 to 6.

      9 and 10 are diagrams showing a photomask modified by the black defect correction method of the present invention.

      As shown in FIG. 4, when a black defect 500 in which an unnecessary mask pattern forming material remains on the substrate 100 of the light transmitting part is conventionally generated, an unnecessary mask is irradiated by irradiating a focused ion beam (FIB) as shown in FIG. 5. The black defect 500 was corrected by removing the pattern forming material.

        However, since the black defect 500 is removed based on the thickness of the mask pattern 150, as shown in 'C' of FIG. 6, a predetermined region of the substrate 100 of the light transmitting part where the black defect exists is lost. Steps are generated with the neighboring substrate 100. Therefore, a phase error occurs due to the step.

        Accordingly, in the present invention, in order to compensate for the above problems, a trench is formed to correct the phase error of the black defect.

       Next, a method of correcting a phase error due to a black defect according to a second embodiment of the present invention will be described in detail with reference to FIGS. 9 and 10.

       9 and 10 are diagrams showing a photomask modified by the black defect correction method of the present invention.

      First, as illustrated in FIG. 9, a black defect 500 adjacent to the mask pattern 150 is formed by using an FIB (Focused Ion Beam) in a mask pattern 150 in which black defects are generated. A trench 400 having a predetermined width and depth is formed along one side.

       FIG. 10 is a cross-sectional view of the photomask shown in FIG. 9 taken along the line 'VIII'.                     

       In particular, the width and depth of the trench 400 are formed in consideration of a phase error due to a difference in transmittance between the black defect 500 and the mask pattern 150 adjacent to the black defect 500.

       Next, embodiments of the present invention will be described in detail. The embodiment of the present invention proceeds under the assumption that the phase error is 180 degrees.

       First, the trench width is fixed to 100 kW and the trench is formed to a depth of up to 2400 kW when using Arf, and to a depth of up to 1900 kW when using Krf.

     Next, in the case of Arf, an exposure process is performed on the photomask having the trench 400 formed to have a depth of 2400 Hz and a width of 100 Hz to determine whether the 180 ° phase error is corrected and returned to normal. In this case, if the phase error is not corrected, the width of both sides of the trench 400 of 100 ms is repeatedly etched by 10 ms to find a point where the error of 180 ° is resolved. Also in the case of Krf, when the 180 ° phase error of the photomask having the trench 400 formed to a depth of 1900 와 and a width of 100 가 is corrected and does not return to normal, the widths of both sides of the trench 400 are changed as described above. Repeatedly add and etch by 10Å to find the point where the error of 180 ° is solved.

      When the phase error correction step is performed as described above, the phase error of the mask pattern adjacent to the black defect is corrected due to the trench, thereby correcting the black defect.

Although the preferred embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improvements of those skilled in the art using the basic concepts of the present invention defined in the following claims are also provided. It belongs to the scope of rights.

       As described above, when the defect correction method of the photomask according to the present invention is applied, in the present invention, the white defect and the black defect are conventionally corrected by performing a simple process of forming a trench along the portion where the white defect and the black defect occur. The phase error that occurs afterwards can be corrected.

      Accordingly, defects in the photomask can be corrected without reworking the photomask, thereby improving process yield.

Claims (6)

      Providing a photomask including a back defect in which a predetermined region of a mask pattern is lost;       A back defect correction step of depositing a compensation film on the lost region of the mask pattern;      And correcting a phase error of the compensation layer with respect to the mask pattern.       The method of claim 1, wherein the phase error correction step forms a trench having a predetermined width and a predetermined depth along one side of the compensation layer not in contact with the mask pattern.        The method of claim 2, wherein the width and depth of the trench are adjusted according to a phase error between the mask pattern and the compensation layer.       Providing a photomask comprising a black defect in which the mask pattern forming material remains on the transparent substrate,       A black defect correction step of removing the mask pattern forming material remaining on the substrate;       And a phase error correction step due to a difference in transmittance between the substrate and the mask pattern where a portion of the region is damaged due to the black defect removal.        5. The method of claim 4, wherein the phase error correction step forms a trench having a predetermined width and depth along one side of the black defect adjacent to the mask pattern.       The method of claim 5, wherein the trench width and depth are adjusted according to a phase error of a substrate in which a partial region is damaged due to mask pattern and black defect removal.

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