JP2006114639A - Method of correcting defective hole pattern of mask - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of improving the dimensional accuracy of a pattern transferred onto a wafer by facilitating the management of the accuracy of a mask pattern, and to obtain a very precise transfer dimensional accuracy especially in correcting a hole pattern for which a pattern region to be formed is restricted. <P>SOLUTION: The method of correcting a defective hole pattern of a mask includes a thin film formation process (S106), wherein a prescribed thin film is formed in an annular shape at a position on the mask where the defective hole pattern is formed; and an etching process (S108) wherein a mask material located inside the inner periphery of the thin film is etched, so that a part inside the inner periphery of the prescribed thin film formed in an annular shape may be an opening portion. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for correcting a defective hole pattern of a mask, and in particular, an electron beam projection exposure for increasing the dimensional accuracy of a transferred pattern in a lithography technique for transferring and forming a fine pattern from a mask in a semiconductor device manufacturing process. The present invention relates to defect correction of a mask used for the above.

Lithography technology, which is responsible for the progress of miniaturization of semiconductor devices, is an extremely important process for generating a pattern among semiconductor manufacturing processes. Conventionally, optical exposure technology has been used in the production of semiconductor devices. In recent years, however, the pattern dimensions of high-density integrated devices such as LSI and VLSI are approaching the limit resolution, and high-resolution exposure technology has been developed. Is an urgent need.
Electron beam (electron beam) exposure technology has inherently excellent resolution, and development of state-of-the-art devices such as DRAM (Dynamic random access memory) and production of some ASIC (application specific integrated circuit). It is used for. However, in the conventional variable shaping type electron beam exposure method, since the pattern is drawn in the manner of one stroke, the wafer processing capacity per unit time, that is, the throughput is low, which is not suitable for mass production of devices.
At present, an electron beam projection (Electron Projection Lithography: EPL) technique for performing divided reduction transfer has been proposed as a next-generation exposure technique, and its research and development has been performed recently.

FIG. 21 is a conceptual diagram for explaining the operation of the EPL exposure apparatus.
First, on a reticle stage in an EPL exposure apparatus, a subfield mask 350 on which a subfield pattern for projecting and transferring a subfield 320 serving as an exposure unit region for one semiconductor chip is formed in a grid pattern. A mask 340 is disposed. The subfield 320 is a region corresponding to one shot when the electron beam 330 (charged particle beam) is irradiated. The subfield mask 350 is formed with various subfield patterns through which the electron beam 330 is transmitted. Then, the electron beam 330 irradiated from the charged particle source is deflected by a deflector and irradiated with a pattern of a predetermined subfield mask 350, and the transmitted electron beam 330 is reduced to ¼ by an electron lens and is reduced to a wafer 300. The subfield pattern formed on the subfield mask 350 is projected and transferred by irradiating the subfield 320 which becomes an exposure unit region in one semiconductor chip region among the plurality of semiconductor chip regions 310 divided above. . Next, the subfield pattern of the subfield mask 350 located next to the column is deflected by a deflector so that the electron beam 330 irradiates, and similarly, the adjacent subfield 320 for the one semiconductor chip is changed. By irradiation, the subfield pattern formed on the subfield mask 350 is projected and transferred to the adjacent subfield 320. This is repeated in sequence, and after irradiating the subfield pattern of the subfield mask 350 in that column, the reticle stage and wafer stage are moved to a position where the top of the subfield mask 350 in the second column can be projected and transferred onto the wafer 300. Then, various subfield patterns of the subfield mask 350 in the second column are sequentially irradiated. In this way, exposure of one semiconductor chip region 310 is completed by irradiating the subfield pattern of the subfield mask 350 of all rows. Such an operation is performed on all the semiconductor chip regions 310 divided on the wafer 300. In addition, the EPL exposure apparatus is described in the following documents (for example, see Patent Document 1, Non-Patent Documents 1 and 2).

Here, when forming a pattern on a mask substrate with respect to an electron beam exposure mask used in an EPL exposure apparatus, a variable shaping electron beam exposure apparatus is used.
FIG. 22 is a conceptual diagram for explaining the operation of the variable shaping electron beam exposure apparatus.
A rectangular aperture 411 for molding the electron beam 330 is formed in a first aperture 410 of a variable shaping type electron beam exposure apparatus (electron beam direct drawing type exposure apparatus: EB (Electron beam) direct drawing apparatus). Yes. Further, the second aperture 420 is repeatedly formed around a variable shaping opening 421 for shaping the electron beam 330 having passed through the opening 411 of the first aperture 410 into a desired rectangular shape, and the variable shaping opening 421. A partial collective mask 422 on which various basic patterns frequently used are formed. The electron beam 330 irradiated from the charged particle source 430 and passed through the opening 411 of the first aperture 410 is deflected by the deflector, passes through a part of the variable shaping opening 421 of the second aperture 420 and passes through the mask 340. Irradiated on top. That is, a rectangular shape that can pass through both the opening 411 of the first aperture 410 and the variable forming opening 421 of the second aperture 420 is directly drawn in a region that becomes the predetermined subfield mask 350 on the mask 340. A method of creating an arbitrary rectangular shape by passing both the opening 411 of the first aperture 410 and the variable forming opening 421 of the second aperture 420 is referred to as a variable forming method. Further, a method of irradiating the entire basic pattern, which is frequently used repeatedly, with the electron beam 330 and creating the basic pattern is referred to as a partial batch method (see, for example, Patent Documents 2 to 5).

FIG. 23 is a view showing a part of an electron beam exposure mask used in the EPL exposure apparatus.
As shown in FIG. 23, as an example of the mask, a stencil mask in which a pattern portion is penetrated by a 2 μm Si (silicon) thin film is used. In electron beam projection exposure, an electron beam passes through the penetrating region and reaches the wafer. On the other hand, where there is Si, the electron dose that reaches the wafer due to scattering of the transmitted electron beam by Si is reduced. On the wafer, a resist whose solubility changes depending on the irradiated electron dose is applied. The solubility changes depending on the exposure amount of the electron beam, and the resist pattern is developed to develop an image of the mask pattern on the wafer. Form. As described above, in electron beam projection exposure using this mask, a mask pattern is reduced and projected onto a wafer on which a semiconductor element is formed, the stage of the electron beam projection exposure apparatus is moved, and transfer is repeatedly performed. Are arranged on the wafer.

  Here, in the process of creating the mask, a defect that does not conform to the desired pattern shape occurs in the formed pattern. However, the defect of the mask is repeatedly transferred by pattern transfer using the pattern. For this reason, the defect is also transferred by all the transfer repeatedly performed when being arranged on the wafer. Therefore, a desired semiconductor device cannot be produced. For this reason, the shape of the mask pattern is inspected on the entire surface so that no mask pattern defect remains, and the detected defect portion is corrected.

FIG. 24 is a diagram for explaining a state of mask defect correction.
As shown in FIG. 24, when a penetration pattern is formed where Si should be left, a thin film is formed in the hollow. At the time of electron beam projection exposure, the electron beam is scattered by this thin film in the same manner as Si. Further, for the defect in which Si remains where the penetrating pattern should be formed, etching for removing the remaining Si is performed. These two types of processing are finer than the mask pattern and are performed in a region of an arbitrary shape, so that a focused ion beam (FIB: focused ion beam) is formed so that only a very small region can be irradiated with gallium (Ga) ions. And etching using Ga ion irradiation and thin film deposition. And such correction is performed locally for every defective part (for example, refer to patent documents 6).

  In addition, a technique for forming a hollow thin film using FIB is disclosed in the literature (see, for example, Patent Document 7), and a technique relating to mask correction using FIB is disclosed in the literature ( For example, see Patent Documents 8 to 10 and Non-Patent Document 3).

Also, although not mask correction, as a method of providing fine through holes with a high aspect ratio in mask formation, a carbon film is formed on Si to leave a region to be processed, and a carbon film is formed as a protective film. As described above, there is disclosed a technique in which vertical processing is performed by irradiating only a window portion with ions (see, for example, Patent Document 11).
JP 2001-319872 A JP 2001-135558 A JP 2000-58424 A JP 2000-269126 A JP 2000-58413 A JP 2000-122267 A JP 2002-139825 A JP 2001-102296 A JP 2003-151882 A Japanese Patent Laid-Open No. 11-204403 JP 2002-141266 A “Nikon Nikon Technology: EPL” http: // www. nikon. co. jp / main / jpn / profile / technology / epl / index.jp / main / jpn / profile / technology / epl / index. htm “Stencil reticle development for electron beam project systems”. Kawata, N .; Katakura, S .; Takahashi, and K.K. Uchikawa, J. et al. Vac. Sci. Technol. B 17, 2864 (1999) “FIB Mask Repair Technology for Electron Projection Lithography”. Yamamoto, 2004 Photomask Japan

FIG. 25 is a diagram for explaining a defect of a mask pattern.
FIG. 25 shows a defect pattern opening 200 in the Si substrate 10 on the mask. The desired shape of the hole pattern 210 is indicated by a two-dot chain line. A region surrounded by the desired hole pattern 210 outside the opening 200 of the defect pattern is a lacking region 275 of the opening, which is a defective portion where excess Si remains. In addition, the region surrounded by the desired hole pattern 210 inside the opening 200 of the defect pattern is a protruding region 276 of the opening which is a defective portion where Si to be left is missing. Such a defective portion is first identified, and the following correction is performed for each defective portion.

FIG. 26 is a diagram for explaining a method of correcting a defect in a mask pattern.
Individually deal with the identified defective parts. First, a thin film is deposited on the protruding region 276 so as to cover the protruding region 276 where Si is missing, and a deposition film 262 is formed. On the other hand, for the insufficient region 275 where excess Si remains, unnecessary Si etching of the insufficient region 275 is performed. Thus, the corrected hole pattern opening 204 is formed.

  Here, in order to miniaturize a semiconductor element, the dimension of a pattern formed on a wafer has to be formed with an accuracy of several nm. In order to obtain this accuracy, it is necessary to manage the dimensions on the mask with high accuracy. However, even if mask correction is performed using FIB, there is a problem that related calibration is required depending on the three-dimensional shape of the Si or deposition film and further on the degree of scattering.

  Furthermore, the shape of the generated defect varies, and correction calibration is required depending on the shape of the defect, the shape of the desired pattern, and the positional relationship between them. In addition, there is a problem that it is difficult to manage accuracy with the corresponding correction method.

  Furthermore, in managing such dimensional accuracy when correcting a defect, it is necessary to control the position of the edge of the corrected pattern with high accuracy. However, managing the position of the edge with high accuracy has a problem that the machining process is difficult to control due to the strength of the FIB at the edge, the supply of gas, the scattering of products, etc., and the machining process becomes unstable. It was.

  An object of the present invention is to provide a method for overcoming the above-described problems, facilitating mask pattern accuracy management, and improving the dimensional accuracy of a pattern transferred onto a wafer, and in particular, a pattern region to be formed. An object of the present invention is to obtain a highly accurate transfer dimensional accuracy in the correction of a hole pattern that is limited.

The defect hole pattern correcting method of the mask of the present invention,
A thin film forming step of forming a predetermined thin film in a ring shape at a position where the defective hole pattern is formed on the mask;
An etching step of etching a mask material located on the inner periphery of the predetermined thin film so that the inner periphery of the predetermined thin film formed in an annular shape becomes an opening;
It is provided with.

  The location to be etched can be clarified by making the inner periphery of the predetermined thin film formed in the ring form an opening. Then, by etching the mask material located on the inner periphery of the predetermined thin film, excess mask material is etched. Furthermore, since the thin film is formed with a predetermined width, the portion where the mask material is missing can be blocked.

  Here, in the thin film formation step of the present invention, it is preferable that a thin film is formed in an annular shape using a focused ion beam and a film forming gas because fine processing can be performed.

  Similarly, in the etching step of the present invention, it is preferable to perform fine processing by etching the inside of the thin film using a focused ion beam and an etching gas.

  Further, in the thin film forming step of the present invention, when the defective hole pattern has a portion that protrudes from a predetermined hole pattern region, the predetermined thin film is formed so as to cover the protruding portion.

  By forming the predetermined thin film so as to cover the protruding portion, the portion where the mask material is missing can be covered. Further, since the thin film is formed in an annular shape, it is possible to cover not the part of the defective hole pattern but the part where the mask material is missing over the entire circumference. As a result, it is possible to eliminate the need for correction for each defective part.

  Furthermore, in the thin film forming step according to the present invention, the predetermined thin film is formed so as to cover a portion of each of the defective hole patterns that protrudes from the predetermined hole pattern region.

  For a plurality of defective hole patterns, the predetermined thin film is formed so that a portion protruding from a predetermined hole pattern region of any defective hole pattern is covered, whereby the predetermined shape having the same shape is formed for the plurality of defective hole patterns. A thin film can be applied.

  Furthermore, in the thin film forming step according to the present invention, the predetermined hole pattern outer periphery is formed to be the inner periphery of the predetermined thin film.

  By making the predetermined inner periphery of the thin film coincide with the outer periphery of the desired hole pattern, it is possible to further improve the accuracy of the corrected hole pattern edge by etching along the inner periphery of the predetermined thin film. In other words, the position of the edge can be managed with high accuracy.

Alternatively, in the thin film formation step of the present invention, the inner periphery of the predetermined thin film is formed so as to be inside the outer periphery of the predetermined hole pattern,
In the etching step, it is preferable that the mask material and the predetermined thin film located on the inner periphery of the predetermined hole pattern are etched so that the inner periphery of the predetermined hole pattern becomes an opening.

  By providing an etching margin by forming the inner periphery of the predetermined thin film to be inside the outer periphery of the predetermined hole pattern, the processing accuracy of the inner peripheral end of the predetermined thin film is not increased. Then, the hole pattern edge portion after correction can be processed with high accuracy by subsequent etching. In other words, the position of the edge can be managed with higher accuracy.

Furthermore, in the thin film formation step of the present invention, the predetermined thin film inner periphery is formed in a square shape with a curved corner.
In the etching step, the mask material located in the curved region and the predetermined thin film are etched regardless of the outer periphery of the predetermined hole pattern.

  By forming it into a square shape with a curved corner, the area inside the predetermined thin film can be made close to the pattern area of the surrounding good pattern shape. Furthermore, in the etching step, the pattern area can be finely adjusted by etching the mask material located in the curved region and the predetermined thin film regardless of the outer periphery of the predetermined hole pattern.

And in the said thin film formation process, it is good to irradiate the area | region which forms the said thin film with a gallium ion.
In such a case, the mask is particularly preferably a mask used for electron beam exposure.

  Irradiation with gallium ions causes gallium ions to enter the thin film. The penetration of the electron beam can be further prevented by the entry of gallium ions.

  Furthermore, in the thin film forming step according to the present invention, the predetermined thin film is formed so that a film thickness of the predetermined thin film is 0.5 μm or more.

  As will be described later, by setting the film thickness of the predetermined thin film to 0.5 μm or more, it is possible to prevent transmission of electron beams through the predetermined thin film. Since transmission of an electron beam can be prevented, a fine pattern with higher resolution can be projected and transferred onto a semiconductor substrate (wafer).

  As described above, according to the present invention, by etching the region located inside the predetermined thin film so that the inside of the predetermined thin film formed in an annular shape having a predetermined width becomes an opening, Localized to the defective part, it can be corrected without corresponding to the shape each time, and the correction processing accuracy can be managed with high accuracy regardless of the shape of the defect. Furthermore, by using the same shape of the annular thin film for a plurality of defect patterns and correcting them in the same procedure, the dimensional error between the defect patterns can be reduced.

Embodiment 1 FIG.
In the correction of the size of the hole of the electron beam projection exposure mask, it is necessary to process the edge portion with high precision when performing a minute correction, but in the FIB used for processing, the reaction at the bottom surface of the edge portion is a normal processing. Compared with conditions such as beam intensity, it is difficult to process with sufficient accuracy. Hereinafter, in the first embodiment, a method for accurately transferring dimensions by electron beam projection exposure using a corrected hole will be described.

FIG. 1 is a flowchart showing the main part of the defective hole pattern correction method for a mask according to the first embodiment.
1, in this embodiment, a series of a hole pattern inspection process (S102), a deposition film region setting process (S104), a deposition film formation process (S106) as an example of a thin film formation process, and an etching process (S108). The process of is implemented.

First, in S (step) 102, a pattern formed on the mask is inspected as a hole pattern inspection step.
FIG. 2 is a diagram for explaining the outline of the hole pattern inspection apparatus.
The shape of the hole pattern of the mask is detected using the EPL mask correction device as the hole pattern inspection device. Here, a description will be given using a stencil mask having an opening for penetrating EPL. In FIG. 2, only the configuration necessary for the description is shown, and other configurations are omitted.
The EPL mask placed on the tilt stage is irradiated with FIB, and secondary electrons generated on the mask surface are detected by a secondary charged particle detector (SED) to obtain a surface image. On the other hand, FIB penetrating through the opening of the mask is collided with a secondary charged particle (SE) converter to generate secondary charged particles, which are detected by SED under the EPL mask and a transmission image is obtained. The defect pattern can be detected by collating the surface image and the transmission image and displaying them on the monitor.

FIG. 3 is a diagram illustrating an example of a defective hole pattern.
FIG. 3 shows a part near the defective hole pattern of the mask. FIG. 3A and FIG. 3B show examples of defect hole patterns having different shapes. 3A shows a defect pattern opening 200 in FIG. 3A and FIG. 3B shows a defect pattern opening 202 in the Si substrate 10 as an EPL mask material. For comparison, a desired hole pattern 210 is indicated by a two-dot chain line and is superimposed on the opening 200 of the defect pattern. As shown in FIGS. 3A and 3B, the shape of the defect hole pattern is various and not uniform. It is necessary to accurately correct such defective hole patterns having different shapes. The shape of the defect hole pattern shown in FIGS. 3A and 3B both has a defect portion where Si remains and a defect portion where Si is missing. However, the present invention is not limited to this, and it goes without saying that the present invention can also be applied to a defective hole pattern having either one of the defective portions. Here, the desired hole pattern 210 may be set to have the same roundness as the peripheral pattern in the corner portion that becomes a square corner in order to match the dimensions of a good pattern that does not need to be corrected. desirable. The dimensional accuracy can be improved by making the roundness of the corner portion the same as that of the peripheral pattern and correcting the remaining differences. Hereinafter, a description will be given of how correction is performed using the defect hole pattern shown in FIG.

In S104, as a deposition film area setting step, a virtual deposition film area is set in the defect hole pattern.
FIG. 4 is a diagram for explaining a state in which a deposition film region is set in the defective hole pattern.
FIG. 4 shows a state in which the deposition film formation region 250 is set, and the deposition film formation region 250 serving as a virtual region is superimposed on the opening 200 of the defect pattern formed on the Si substrate 10. Here, the deposition film forming region 250 is set to an annular region having a predetermined width. Regardless of defects with Si remaining or defects with Si missing, a desired pattern can be formed in an area of an appropriate size to cover defects with Si missing that require thin film deposition. The deposition region of the thin film is set so that the region of the desired pattern becomes an opening by being inverted. In other words, the inner periphery of the deposition film formation region 250 is made to coincide with the outer periphery of the desired hole pattern 210. By matching with the outer periphery of the desired hole pattern 210, the edge of the hole pattern can be made clear at the inner periphery of the deposition film. The outer periphery of the deposition film formation region 250 is set not only to cover all the protruding portions of one defective hole pattern but also to cover all the protruding portions of a plurality of defective hole patterns. By covering all the protruding portions of one defective hole pattern, it can be corrected without dealing with each defective portion. Furthermore, by setting so as to cover all protruding portions of the plurality of defective hole patterns, the same deposition film forming region 250 can be used for the plurality of defective hole patterns. Since the same deposition film forming region 250 can be used for a plurality of defect hole patterns, calibration of correction associated with the shape of a defect, the shape of a desired pattern, and the positional relationship between them can be omitted. By using the same deposition film formation region 250 for a plurality of defect hole patterns, it is possible to perform pattern correction by a similar processing procedure to be described later even with various defect shapes, and to improve the dimensional accuracy between the plurality of defect hole patterns. It can be managed to a higher state. Here, the deposition film formation region 250 may be determined after inspecting all the hole patterns on the mask, but is not limited thereto, and is practically set based on the statistical values of the area and shape of the surrounding similar pattern. It doesn't matter. For example, a plurality of connected patterns may be used. Or you may set from the finishing shape estimated by simulation etc. from the layout data of a pattern. For example, a predicted finished shape may be prepared as a template and set from there. A suitable setting can also be performed by this method.
Here, the outer periphery is also rectangular, but the outer periphery is not limited to this, and may be set so as to be an area of an appropriate size so as to cover a defect lacking necessary Si. Therefore, for example, even when the rectangle is set, the width of each side may be different.

In S106, a deposition film is formed in the deposition film formation region 250 as a deposition film formation step.
FIG. 5 is a diagram for explaining a method of forming a deposition film.
A thickness capable of sufficiently shielding electrons incident at high acceleration during EPL exposure by irradiating FIB to the deposition film forming region 250 and injecting a deposition gas 142 which is a deposition reaction gas to perform chemical vapor deposition (CVD). Make a depot. In FIG. 5, a Ga ion beam 112 is used as the FIB. Ga ions enter the deposition film 260 formed by irradiation with a Ga ion beam. By entering Ga ions, it is possible to make it difficult to transmit electrons, and it is possible to form a deposition film 260 that can shield electrons more. The deposition film 260 can also be formed by using an electron beam (EB) or argon (Ar) ion in addition to Ga ions as the FIB. Since the deposition film 260 is deposited on the surface of the Si substrate 10 and has a high growth rate at the edge portion, deposition (film formation) proceeds on the hollow. Therefore, it can form so that the defect site | part which Si is missing may be covered.
The deposition film 260 is preferably composed of a carbon-based material. The deposition gas 142 is necessarily preferably composed mainly of a carbon-based material. For example, diamond-like carbon (DLC) or the like can be used as the deposition film 260. An aromatic gas such as phenanthrene can be used as the film forming gas 142.
In addition, the thickness of the deposition film 260 that can sufficiently shield electrons incident at a high acceleration during EPL exposure is desirably 0.5 μm or more as described later.

FIG. 6 is a diagram for explaining the outline of the EPL mask correcting apparatus.
In the EPL mask correcting apparatus 100, ions are extracted from an ion source 110 such as liquid gallium, and the ions are focused and accelerated in a beam shape through an ion optical system 120 such as an electron lens. The focused and accelerated ion beam 112 is deflected by a deflector and irradiates a predetermined region of the mask 340 disposed on the mask stage 150 as a focused ion beam. At that time, a film forming gas 142 is injected from the gas gun 140 to form a film in the predetermined region by chemical vapor deposition (CVD). Next, a deflector is deflected so that the ion beam 112 irradiates the adjacent region, and similarly, a deposition film is grown to the adjacent region. The position on the mask to be irradiated can be grasped by detecting secondary electrons generated by irradiation of the ion beam 112 with the secondary charged particle detector 130.

In S108, as the etching process, a region having a desired pattern, that is, a processing region is set in the inner opening of the deposition film 260, and similarly, this region is irradiated with FIB, and an etching reaction gas is injected to irradiate the region. The unnecessary Si inside is removed.
FIG. 7 shows a region to be etched.
An annular deposition film 260 is formed in the opening 200 of the defect pattern on the Si substrate 10 with the outer periphery of the desired hole pattern as the inner periphery. Then, an extra Si region existing inside the inner periphery of the deposition film 260 becomes an etching region 270.

FIG. 8 is a diagram for explaining a method of etching.
Etching gas 144 is sprayed onto the etching region 270 to cause the etching gas molecules 146 to be adsorbed on the surplus Si surface, and FIB is irradiated to etch surplus Si by gas assist etching. The apparatus described in FIG. 6 may be used, or the apparatus may be processed by another similar apparatus, and thus description of the apparatus configuration, operation, and the like will be omitted. Further, since a natural oxide film (SiO ₂ ) is formed on the necessary Si surface located outside the deposition film 260, even if the etching gas 144 is blown to the part not irradiated with FIB, the part is etched. It will never be done.
In FIG. 8, a Ga ion beam 112 is used as the FIB. Etching can also be performed using electron beam (EB) or argon (Ar) ions in addition to Ga ions as FIB. As the etching gas 144, a halogen-containing material gas is desirable. For example, Xe ₂ F, CF ₄ , CHF ₃ , Cl ₂ , CHCl ₃ , I ₂ or the like may be used.

FIG. 9 is a diagram for explaining a technique for etching.
When etching excess Si, as shown in FIG. 9A, a Ga ion beam 112 is irradiated to a 1-shot region 114 of about 7 nm for 2 μs and then deflected by a deflector. As shown in 9 (b), processing is performed while sequentially moving the shot areas. Here, for simplification of description, a defect pattern in which a large amount of excess Si is left as shown by the defect pattern opening 205 is described. When scanning is performed on the opening 205 of the defect pattern, blanking is performed with a blanking mask (not shown) of the apparatus so that the Ga ion beam 112 is not irradiated onto the mask. By sequentially shooting not only the region along the inner periphery of the deposition film 260 but also the region where excess Si remains, it is possible to prevent redeposition of Si even in a hole pattern having a small diameter of 260 nm, for example.

FIG. 10 is a diagram illustrating a hole pattern after correction.
As shown in FIG. 10, a desired modified hole pattern 203 can be formed inside an annular deposition film 260 formed on the Si substrate 10 so as to cover a region lacking necessary Si.

FIG. 11 is a diagram showing a defect pattern having no defect lacking Si.
As shown in FIG. 11, the present embodiment can be applied even when a defect pattern opening 206 in which excess Si remains is formed on the Si substrate 10 with respect to the desired hole pattern 210.

FIG. 12 is a diagram for explaining a method of applying the present embodiment to a defect pattern having no defect lacking Si.
As shown in FIG. 12, also in this case, by setting a deposition film formation region 250 having the same shape as other defective hole patterns and forming the deposition film 260 in the deposition film formation region 250, the entire circumference of the edge is reduced. It is only a deposition film with Si, and correction processing can be performed as a structure similar to the correction of a defect having a portion lacking Si. By using a similar method, it is possible to share dimensions.

FIG. 13 is a diagram showing the dependency of the EPL transfer dimension on the film thickness of the deposition film.
Here, a DLC film was used as the deposition film. As shown in FIG. 13, when the film thickness of the deposition film is smaller than 0.5 μm (500 nm), the difference between the mask dimension and the dimension transferred to the EPL on the wafer is large, and the film thickness of the deposition film is about 0.1 mm. In the case of 5 μm or more, it can be seen that there is little deviation between the mask dimension and the dimension EPL transferred on the wafer. In other words, when the film thickness of the deposition film is smaller than 0.5 μm, the electron beam cannot be sufficiently shielded. Therefore, the dimensional accuracy can be increased by forming the deposition film with a thickness of 0.5 μm or more.

  As described above, since the processing is performed in the same procedure regardless of various uneven shapes, the dimensional controllability can be improved. When performing correction processing using this method in a unified manner for various defect shapes, the three-dimensional structure of the edge portion of the pattern after correction processing can sufficiently shield electrons incident at high acceleration regardless of the defect type. Only the deposition film or the deposition film and Si is laminated. Here, since the film thickness is sufficient to obtain the electron beam shielding effect of the deposition film, the required dimensional calibration can reduce the dependency on the variation of the defect shape. Therefore, it becomes possible to perform simple correction, and the dimensional accuracy through the defect type can be improved.

Embodiment 2. FIG.
In the second embodiment, a method in which a process for correcting a dimension is further added to the method of the first embodiment will be described.
FIG. 14 is a diagram showing a mask cross section after correction.
When the defective hole pattern of the mask is corrected by the method of the first embodiment, in the formation of the deposition film as shown in FIG. 14, the end of the deposition film 260 formed on the Si substrate 10 has a desired hole pattern size. If there is a part that is not enough, the dimension of the modified hole pattern is also inaccurate. Therefore, in the second embodiment, a method for solving such a problem will be described. Each process flow is the same as in FIG.

FIG. 15 is a diagram showing a state before the etching process in the second embodiment.
In the deposition film region setting step, a desired hole is formed as shown in FIG. 15 when setting a thin film deposition film formation region having a desired pattern inverted and performing deposition capable of sufficiently shielding electrons incident at high acceleration. A large number of deposition film forming regions are formed by increasing the number of depositing regions inside the pattern 210. Then, in the deposition film forming step, the deposition film 260 is formed in the deposition film formation area where the deposition area is increased inside.

FIG. 16 is a diagram for explaining a method of etching.
As shown in FIG. 16A, the region of the desired hole pattern 210 is used as an etching region 270, and the FIB is irradiated, so that an unnecessary deposition film in this region is formed as shown in FIG. 16B. 260 is removed by sputtering. As shown in FIG. 16C, when unnecessary Si exists in the region of the desired hole pattern 210, an etching gas 144 is sprayed onto the etching region 270 to etch etching gas molecules onto the surplus Si surface. Excess Si is etched by a gas assist etching method by adsorbing 146 and irradiating FIB. The apparatus described in FIG. 6 may be used, or the apparatus may be processed by another similar apparatus, and thus description of the apparatus configuration, operation, and the like will be omitted.
As in the first embodiment, a Ga ion beam 112 is used as the FIB. Etching can also be performed using electron beam (EB) or argon (Ar) ions in addition to Ga ions as FIB. As the etching gas 144, a halogen-containing material gas is desirable. For example, Xe ₂ F, CF ₄ , CHF ₃ , Cl ₂ , CHCl ₃ , I ₂ or the like may be used. Here, when a carbon film such as DLC is used as the deposition film 260, the deposition film 260 does not react with the etching gas 144, and therefore is removed by sputtering using FIB.

  The other steps are the same as those in the first embodiment, and will be omitted.

  As described above, according to the second embodiment, since the etching allowance (cutting allowance) is provided in the deposition film 260 formed on the Si substrate 10, the problem that the desired hole pattern size is insufficient is solved. be able to.

In addition, when forming the deposition film, the edge portion may have a three-dimensional shape different from that of the flat portion, and when an unnecessary protrusion as shown in FIG. The deposition film 260 is not etched with the halogen gas and is removed by sputtering with FIB, and therefore takes longer than the etching with the halogen gas. In the first embodiment, when such an unnecessary protrusion is formed at the end of the deposition film 260, in the first embodiment, it is not assumed that the deposition film 260 is sputtered by FIB, so that an unnecessary protrusion remains. It can also be considered. Therefore, according to the second embodiment, since it is assumed that the deposition film 260 is sputtered by FIB from the beginning, such a protrusion can also be removed.
As described above, according to the second embodiment, even when the edge portion has a three-dimensional shape different from that of the flat portion when the deposition film is formed, this portion is processed uniformly with the FIB so It is possible to prevent the dimensional shift from varying.

FIG. 17 is a diagram showing the correction accuracy.
When the defective hole pattern was corrected using the method of the first embodiment or the second embodiment, the result as shown in FIG. 17A was obtained. When the EPL exposure transfer was performed on the wafer using the mask, the post-transfer dimensions on the wafer were obtained as shown in FIG. By correcting the defective hole pattern, the dimensions can be greatly improved compared to before the correction.

Embodiment 3 FIG.
In the third embodiment, a mode in which a process for correcting a dimension with higher accuracy than that in the first or second embodiment is added will be described.
FIG. 18 is a flowchart showing the main part of the defect hole pattern correction method for a mask in the third embodiment.
18, in this embodiment, after the hole pattern inspection process (S102), the deposition film region setting process (S104), the deposition film forming process (S106) as an example of the thin film forming process, and the etching process (S108). Furthermore, a series of steps of a defective hole pattern re-inspection step (S110) and a corner etching step (S112) are performed.

  In FIG. 18, the hole pattern inspection step (S102) may be the same as that in the first embodiment or the second embodiment, and thus the description thereof is omitted.

Here, the transfer dimension of the hole pattern is more correlated with the area than the position of the local edge. Therefore, the accuracy can be improved by matching the area with a better peripheral pattern.
FIG. 19 is a diagram showing a corrected hole pattern that has been completed up to the etching step (S108).
As a modified hole pattern that has been completed up to the etching step (S108), a deposition film 260 is formed in an annular shape on the Si substrate 10 and the inside thereof is etched. Here, in the deposition film region setting step, a corner portion is formed. The deposition film forming region is set so that the cutting allowance 214 for area adjustment remains, and the deposition film 260 is formed in the deposition film forming region in the deposition film forming step. In the etching process, the inside of the deposition film 260 is etched. Here, as described in the second embodiment, the deposition film 260 is formed so that the deposition film 260 is formed on the inner side of the desired hole pattern 210, and the inside of the desired hole pattern 210 is etched to remove the excess. The deposition film 260 may be etched together with Si. However, even in such a case, the cutting margin 214 for area adjustment is left in the corner portion.

  In S110, as a defective hole pattern re-inspection process, the area of the corrected hole pattern that has been completed up to the etching process (S108) is measured. The measurement may be performed by detecting the position by the same method as the hole pattern inspection process and measuring the area from the data.

  In S112, as the corner etching process, the corner portion is etched with respect to an error from a desired pattern area, so that the correction is performed by changing the curvature of the corner portion.

FIG. 20 is a diagram for explaining the area adjustment allowance.
FIG. 20A shows a case where area adjustment is performed using the side of the hole pattern. FIG. 20B shows a case where the area adjustment is performed using the corner portion of the hole pattern. As can be seen from the cross-sectional views of FIG. 20A and FIG. 20B, the adjustment allowance t1 when the area adjustment is performed using the corner portion rather than the adjustment allowance t2 when the area adjustment is performed using the side. Is bigger. In other words, a large flat portion for adjustment can be taken. A larger adjustment allowance for a flat portion that is perpendicular to the FIB irradiation direction than an edge portion that is parallel to the FIB irradiation direction can be processed more easily, and dimensional accuracy can be improved. it can.

  As described above, in the third embodiment, a thin film deposition region in which a desired pattern is inverted is set, deposition is performed more than the desired pattern, and unnecessary in the next desired pattern region. When removing the Si and the edge of the deposition film, or after removing the edge, the curvature of the corner is changed so as to be the same as the area of the desired region. Do and adjust. The accuracy after the correction shown in FIG. 17 can be further improved by adjusting the curvature by changing the curvature of the corner portion.

  Further, as described above, the removal processing of the edge portion is difficult in terms of FIB strength, gas supply, product scattering, and the like of the edge portion as compared with the flat portion. Therefore, the machining process becomes unstable. Therefore, it is difficult to maintain good edge position accuracy. Compared with the case where the machining margin t2 of the side portion as shown in FIG. 20 (a) is small and is processed substantially over the entire circumference of the edge portion, the corner portion as shown in FIG. 20 (b) is mainly processed. However, the processing of the flat portion with high accuracy increases, and the accuracy of matching the area can be improved.

  The embodiments have been described above with reference to specific examples. However, the present invention is not limited to these specific examples.

  In addition, all mask correction methods that include elements of the present invention and that can be appropriately modified by those skilled in the art are included in the scope of the present invention.

3 is a flowchart showing a main part of a defective hole pattern correction method for a mask in the first embodiment. It is a figure for demonstrating the outline | summary of a hole pattern inspection apparatus. It is a figure which shows an example of a defect hole pattern. It is a figure for demonstrating the state which set the deposition film area | region to the defect hole pattern. It is a figure for demonstrating the method of forming a deposition film. It is a figure for demonstrating the outline | summary of an EPL mask correction apparatus. It is a figure which shows the area | region to etch. It is a figure for demonstrating the method to etch. It is a figure for demonstrating the method to etch. It is a figure which shows the hole pattern after correction. It is a figure which shows the defect pattern without the defect which Si lacked. It is a figure for demonstrating the method of applying this Embodiment to the defect pattern without the defect which Si lacked. It is a figure which shows the film thickness dependence of the deposition film of an EPL transfer dimension. It is a figure which shows the mask cross section after correction. It is a figure which shows the state before the etching process in Embodiment 2. FIG. It is a figure for demonstrating the method to etch. It is a figure which shows correction precision. 10 is a flowchart showing a main part of a defective hole pattern correction method for a mask in a third embodiment. It is a figure which shows the hole pattern after correction completed to an etching process (S108). It is a figure for demonstrating an area adjustment allowance. It is a conceptual diagram for demonstrating operation | movement of an EPL exposure apparatus. It is a conceptual diagram for demonstrating operation | movement of a variable shaping type | mold electron beam exposure apparatus. It is a figure which shows a part of mask for electron beam exposure used for an EPL exposure apparatus. It is a figure for demonstrating the mode of the defect correction of a mask. It is a figure for demonstrating the defect of a mask pattern. It is a figure for demonstrating the method to correct the defect of a mask pattern.

Explanation of symbols

10 Si substrate 100 EPL mask correction device 110 Ion source 112 Ion beam 114 One shot region 120 Ion optical system 130 Secondary charged particle detector 140 Gas gun 150 Mask stage 142 Film forming gas 144 Etching gas 146 Etching gas molecules 200, 202, 205, 206 Defect pattern opening 203 Corrected hole pattern 204 Hole pattern opening 210 Desired hole pattern 250 Deposition film forming area 260 Deposition film 270 Etching area 275 Insufficient area 276 Protruding area 300 Wafer 310 Semiconductor chip area 320 Subfield 330 Electron beam 340 Mask 350 Subfield mask 410 Aperture 411 Opening 420 Aperture 421 Variable shaping opening 422 Partial lump mask 430 Charged particle source

Claims (10)

A thin film forming step of forming a predetermined thin film in a ring shape at a position where the defective hole pattern is formed on the mask;
An etching step of etching a mask material located on the inner periphery of the predetermined thin film so that the inner periphery of the predetermined thin film formed in an annular shape becomes an opening;
A defect hole pattern correcting method for a mask, comprising:   2. The defect hole pattern correcting method for a mask according to claim 1, wherein in the thin film forming step, the thin film is formed in an annular shape using a focused ion beam and a film forming gas.   2. The method for correcting a defective hole pattern in a mask according to claim 1, wherein in the etching step, the inside of the thin film is etched using a focused ion beam and an etching gas.   The said thin film is formed so that the part which protrudes may be covered in the said thin film formation process, when a defect hole pattern has a part which protrudes a predetermined | prescribed hole pattern area | region. Mask defect hole pattern correction method.   The said thin film is formed in the said thin film formation process so that the part which protrudes a predetermined | prescribed hole pattern area | region may cover all the defective hole patterns about a several defective hole pattern. A method for correcting a defective hole pattern in a mask.   6. The method for correcting a defective hole pattern in a mask according to claim 1, wherein, in the thin film forming step, a predetermined hole pattern outer periphery is formed to be an inner periphery of the predetermined thin film. In the thin film formation step, the inner periphery of the predetermined thin film is formed to be inside the outer periphery of the predetermined hole pattern,
6. The etching step of etching the mask material and the predetermined thin film located inside the predetermined hole pattern outer periphery so that the inner periphery of the predetermined hole pattern is an opening. The defect hole pattern correction method of any one of masks. In the thin film forming step, the predetermined thin film inner periphery is formed in a square shape with a curved corner.
8. The defect hole pattern correction of a mask according to claim 6 or 7, wherein in the etching step, the mask material located in the curved region and the predetermined thin film are etched regardless of the outer periphery of the predetermined hole pattern. Method. In the thin film formation step, a region where the thin film is formed is irradiated with gallium ions,
9. The method of correcting a defective hole pattern in a mask according to claim 1, wherein the mask is a mask used for electron beam exposure.   10. The defect hole pattern correction method for a mask according to claim 1, wherein in the thin film forming step, the predetermined thin film is formed so that a film thickness of the predetermined thin film is 0.5 μm or more. .

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