JP2008256759A - Method for correcting defect in gray tone mask, method for manufacturing gray tone mask and gray tone mask, and method for transferring pattern - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for correcting a defect in a gray tone mask, by which the defect occurring in a light semitransmitting part can be suitably corrected. <P>SOLUTION: The method for correcting the defect in a gray tone mask 20 having a light shielding part 21, a light transmitting part 22 and a light semitransmitting part 23 that reduces a predetermined quantity of the transmitted quantity of exposure light to be used in the use of the mask, the mask for forming a resist pattern having the film thickness gradually or continuously varying on a transfer material, includes the steps of: identifying a defect region in the light semitransmitting part 23 comprising a light semitransmitting film 26; and forming a correction film 27 in a region including the defect region. The correction film 27 has a region in a peripheral part around the center part, the region where the transmitted quantity of exposure light is larger than in the center part. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

 The present invention relates to a gray-tone mask defect correcting method, a gray-tone mask manufacturing method, a gray-tone mask, and a pattern transfer method used for manufacturing a liquid crystal display (LCD). More particularly, the present invention relates to a gray-tone mask defect correcting method, a gray-tone mask manufacturing method, and a gray-tone mask, which are preferably used for manufacturing a thin-film transistor substrate (TFT substrate) used for manufacturing a thin-film transistor liquid crystal display device.

  At present, in the field of LCD, a thin film transistor liquid crystal display (hereinafter referred to as TFT-LCD) is advantageous in that it is thinner and has lower power consumption than a CRT (cathode ray tube). Commercialization is progressing rapidly. A TFT-LCD includes a TFT substrate having a structure in which TFTs are arranged in pixels arranged in a matrix, and a color filter in which red, green, and blue pixel patterns are arranged corresponding to each pixel. It has a schematic structure superimposed under the intervention of. In TFT-LCD, the number of manufacturing processes is large, and the TFT substrate alone is manufactured using 5 to 6 photomasks. Under such circumstances, a method of manufacturing a TFT substrate using four photomasks has been proposed (for example, Non-Patent Document 1 below).

  In this method, the number of masks to be used is reduced by using a photomask (hereinafter referred to as a gray tone mask) having a light shielding portion, a light transmitting portion, and a semi-light transmitting portion (gray tone portion). Here, the semi-transparent portion means that when a pattern is transferred to a transfer object using a mask, the amount of exposure light transmitted therethrough is reduced by a predetermined amount, and the photoresist film on the transfer object after development is developed. A part that controls the amount of remaining film is referred to as a gray-tone mask.

FIG. 5 and FIG. 6 (FIG. 6 is a continuation of the manufacturing process of FIG. 5) show an example of a manufacturing process of a TFT substrate using a gray tone mask.
A metal film for a gate electrode is formed on the glass substrate 1, and the gate electrode 2 is formed by a photolithography process using a photomask. Thereafter, the gate insulating film 3, the first semiconductor film 4 (a-Si), the second semiconductor film 5 (N + a-Si), the source / drain metal film 6, and the positive photoresist film 7 are formed (FIG. 5). (1)). Next, the positive photoresist film 7 is exposed and developed using the gray tone mask 10 having the light shielding portion 11, the light transmitting portion 12, and the semi-light transmitting portion 13, thereby developing the TFT channel portion and the source / drain forming region. Then, the first resist pattern 7a is formed so as to cover the data line formation region and to make the channel portion formation region thinner than the source / drain formation region (FIG. 5B). Next, the source / drain metal film 6 and the second and first semiconductor films 5 and 4 are etched using the first resist pattern 7a as a mask (FIG. 5 (3)). Next, the thin resist film in the channel portion formation region is removed by ashing with oxygen to form a second resist pattern 7b (FIG. 6 (1)). Thereafter, using the second resist pattern 7b as a mask, the source / drain metal film 6 is etched to form the source / drains 6a and 6b, and then the second semiconductor film 5 is etched (FIG. 6 (2)). The remaining second resist pattern 7b is peeled off (FIG. 6 (3)).

  As a gray-tone mask used here, one having a structure in which a semi-translucent portion is formed in a fine pattern is known. For example, as shown in FIG. 7, the light-shielding portions 11a and 11b corresponding to the source / drain, the translucent portion 12, and the semi-transparent portion (gray tone portion) 13 corresponding to the channel portion are provided. The light part 13 is an area where a light shielding pattern 13a composed of a fine pattern below the resolution limit of an LCD exposure machine using a gray tone mask is formed. Both the light shielding portions 11a and 11b and the light shielding pattern 13a are usually formed from films of the same thickness made of the same material such as chromium or a chromium compound. In many cases, the resolution limit of an exposure apparatus for LCD using a gray-tone mask is about 3 μm for a stepper type exposure machine and about 4 μm for a mirror projection type exposure machine. For this reason, for example, in FIG. 7, the space width of the transmission part 13b in the semi-transmission part 13 can be less than 3 μm, and the line width of the light shielding pattern 13a can be less than 3 μm which is less than the resolution limit of the exposure machine.

  The above-described fine pattern type semi-transmission part is a line-and-space type of fine pattern for gray tone design, specifically, to provide a halftone effect intermediate between the light-shielding part and the light-transmission part. There is a choice of whether it is a dot (halftone dot) type or other pattern, and in the case of the line and space type, what is the line width, the part where light is transmitted and the part where light is blocked The ratio can be designed in consideration of what should be done and how much the overall transmittance is designed.

  On the other hand, it has been conventionally proposed to use a semi-transparent half-tone film (semi-transparent film) for a portion where half-tone exposure is desired (for example, Patent Document 1 below). By using this halftone film, halftone exposure can be performed while reducing the exposure amount of the halftone portion. When using a halftone film, consider how much the overall transmittance is required in the design, and in the mask, it is possible to produce a mask by selecting the film type (material) of the halftone film or the film thickness. Become. In mask manufacturing, the film thickness of the halftone film is controlled. When the TFT channel part is formed with the gray tone part of the gray tone mask, if it is a halftone film, it can be easily patterned by a photolithography process, so that it is possible even if the TFT channel part has a complicated pattern shape. There are advantages.

  Further, in Patent Document 2 below, when correcting a defect in a gray tone part in a gray tone mask having a light shielding part, a light transmitting part, and a gray tone part, the film of the gray tone part has a normal gray tone effect. It describes a reduction in film thickness or film formation by etching using FIB (Focused Ion Beam Deposition) so as to obtain a film thickness as obtained.

JP 2002-189280 A JP 2004-309515 A “Monthly FP Intelligence”, May 1999, p. 31-35

In the gray tone mask described in Patent Document 1 as described above, it is inevitable that defects occur in the gray tone portion formed of the semi-transparent film.
On the other hand, according to Patent Document 2, in a gray tone mask having a fine pattern in a gray tone portion, it is possible to relatively easily correct a defect generated in the fine pattern portion with a high degree of correction. ing. That is, if the normal pattern is fine and it is difficult to restore the fine pattern to the same shape when a defect occurs, a light shielding film is formed on the white defect portion using, for example, a laser CVD apparatus. Alternatively, the method of removing the black defect portion and forming the light shielding film again solves the problem that it is not easy to control the transmittance for obtaining an appropriate gray tone effect.
Here, a defect whose transmittance is lower than a predetermined value due to an excess of the film pattern, adhesion of a light shielding film component, or foreign matter is referred to as a black defect, and a defect whose transmittance is higher than a predetermined value due to a lack of the film pattern is referred to as a white defect. .

  On the other hand, in a gray-tone mask of a type that controls the amount of exposure light transmitted by using a semi-transparent film in the semi-transparent part, ideally when a white defect occurs due to the lack of the semi-transparent film. It is sufficient that the correction film having the same size and shape as the missing defect portion can be corrected with high positional accuracy. In the case of a black defect, it is only necessary to form a correction film having the same size and shape as the removed portion after removing the film of the black defect portion. However, such correction is practically difficult. For example, if a film portion formed for defect correction overlaps with a defect peripheral portion, the light transmission amount of that portion becomes lower than a desired value, which may cause a new black defect. Alternatively, if there is a gap between the film portion formed for defect correction and the peripheral edge portion of the defect, the light transmittance of that portion becomes equal to that of the translucent portion, resulting in a white defect.

  The above problem will be described with reference to FIGS. 8 and 9 show an example of a gray tone mask in which such a semi-transparent portion is a halftone film (semi-transparent film). That is, the gray tone mask 60 includes a light shielding portion 61, a light transmitting portion 62, and a semi-light transmitting portion 63 that are formed in a predetermined pattern, and the light shielding portion 61 has a light shielding film 65 on a transparent substrate 64. The translucent part 62 is composed of a portion where the transparent substrate 64 is exposed, and the semi-translucent part 63 is composed of a semi-transparent film 66 on the transparent substrate 64 (for example, (2) in FIG. 9A (refer to a cross-sectional view taken along line LL in (1)).

As shown in FIG. 8A, when a white defect 70 is generated due to the lack of the semi-transparent film in the semi-transparent portion 63, the correction film 67 having the same size and the same shape as the missing white defect portion is positioned accurately. If it can be formed high ((b) in the figure), ideal correction can be performed. However, such an ideal correction is actually difficult. For example, as shown in FIG. 9A, since the white defect region 70 and the film formation region 71 of the correction film 67 are shifted, the correction film 67 is defective. When a region 70b that overlaps with the peripheral portion and a region 70a of a gap formed between the correction film 67 and the defective peripheral portion are generated, the same figure (3) (representing the light transmittance (T) in the cross section shown in (2)). As shown, the light transmission amount in the former overlapping region 70b is lower than a desired value (closer to the light shielding portion), and there is a possibility that a new black defect is formed. Further, the light transmittance in the latter gap region 70a is equal to that of the light transmitting portion, resulting in a white defect.
Further, as shown in FIG. 9B, light is transmitted as described above in the region 70b where the correction film 67 overlaps the defect peripheral portion, which is generated because the film formation region 72 of the correction film 67 is larger than the white defect region 70. The rate may be lowered and black defects may be formed. Further, as shown in FIG. 9C, in the region 70a of the gap between the correction film 67 and the defect peripheral portion, which is generated because the film formation region 73 of the correction film 67 is smaller than the white defect region 70, as described above. It becomes a white defect.

  The present invention has been made in view of the above-described conventional problems, and a first object of the present invention is to provide a defect correction method for a gray tone mask that can suitably correct a defect generated in a semi-translucent portion. The second object of the present invention is to provide a method for manufacturing a gray-tone mask having a defect correcting step to which such a defect correcting method is applied. Furthermore, it is a third object to provide a gray tone mask in which defects generated in the semi-transparent portion are suitably corrected. It is a fourth object of the present invention to provide a pattern transfer method using the gray tone mask.

In order to solve the above problems, the present invention has the following configuration.
(Structure 1) A light-shielding portion, a light-transmitting portion, and a semi-light-transmitting portion that reduces a transmission amount of exposure light used when using a mask by a predetermined amount, and the film thickness is stepwise or continuous on the transfer target. A gray tone mask defect correcting method for forming a different resist pattern in which the semi-translucent portion is formed of a semi-transparent film, and a defect region is specified in the semi-transparent portion; and the defect A correction film is formed in a region including the region, and the correction film has a region where the amount of exposure light transmitted is larger than that in the central portion in a portion on the peripheral side of the central portion. This is a defect correction method for a gray-tone mask.
(Structure 2) The gray-tone mask defect correcting method according to Structure 1, wherein the correction film increases the amount of exposure light transmitted continuously or stepwise from the center to the periphery. It is.
(Structure 3) The gray-tone mask defect correcting method according to Structure 1, wherein the correction film has a region having a film thickness smaller than that of the central portion at a peripheral portion of the correction film.
(Structure 4) The gray-tone mask defect correcting method according to Structure 3, wherein the thickness of the correction film decreases continuously or stepwise from the center to the periphery.

(Configuration 5) Since the defect region has a portion where the thickness of the semi-translucent film is small or the semi-transparent film is missing with respect to a normal semi-transparent portion, the amount of exposure light transmitted is normal. 5. The gray-tone mask defect correcting method according to any one of configurations 1 to 4, wherein the region is larger than a semi-translucent portion.
(Structure 6) The defect region has a normal amount of exposure light transmitted because the film thickness of the semi-translucent film is large or components other than the semi-translucent film adhere to the normal semi-transparent portion. 5. The gray tone mask defect correcting method according to any one of Structures 1 to 4, wherein the defect correcting area is smaller than a semi-translucent portion.

(Structure 7) The correction film forming process includes two or more film forming processes, and in each film forming process, the transmission is larger than the amount of exposure light that gives a desired gray tone effect in the semi-translucent portion. The gray-tone mask defect correcting method according to any one of Structures 1 to 6, wherein a semi-transparent film having an amount is formed.
(Structure 8) The correction film is formed twice or more in the defect region, the step of forming a film in the region smaller than the defect region, and the step of forming the film in the region including the defect region and larger than the defect region. The defect correction method for a gray-tone mask according to Configuration 7, including the defect correction method.
(Structure 9) The gray-tone mask defect correcting method according to any one of Structures 1 to 8, wherein the correction film forming step applies a focused ion beam method.
(Structure 10) The defect correction method for a gray-tone mask according to Structure 9, wherein the ion beam is irradiated in a defocused state.

(Structure 11) A gray-tone mask manufacturing method including a defect correcting step by the defect correcting method according to any one of structures 1 to 10.
(Configuration 12) A light-shielding portion, a light-transmitting portion, and a semi-light-transmitting portion that reduces a transmission amount of exposure light used when using a mask by a predetermined amount, and the film thickness is stepwise or continuous on the transfer target. A gray-tone mask for forming different resist patterns, wherein the semi-translucent portion is formed of a semi-transparent film, and a predetermined portion of the semi-transparent film is a portion on the peripheral side from the center portion In addition, the gray-tone mask is characterized in that a correction film having a region where the amount of transmitted exposure light is larger than that of the central portion is formed.

(Structure 13) The gray-tone mask according to Structure 12, wherein the correction film has a large amount of exposure light transmitted continuously or stepwise from the center to the periphery. .
(Structure 14) The gray-tone mask according to Structure 12, wherein the correction film has a region having a thickness smaller than that of the central portion at a portion on the peripheral side of the central portion.
(Structure 15) The gray-tone mask according to Structure 14, wherein the correction film has a film thickness that decreases continuously or stepwise from the center to the periphery.
(Structure 16) Using the graytone mask according to the manufacturing method according to Structure 11 or the graytone mask according to any one of Structures 12 to 15 and an exposure machine, a pattern formed on the graytone mask is transferred. It is a pattern transfer method characterized by transferring to a body.

According to the gray-tone mask defect correcting method of the present invention, the semi-transparent portion is formed of a semi-transparent film, the step of identifying the defect region in the semi-transparent portion, and the correction film in the region including the defect region The correction film has a region where the amount of exposure light transmitted is larger than that of the central portion in the peripheral portion of the correction film.
Even when the correction film overlaps the defect peripheral part, it is possible to suppress a decrease in the light transmission amount of the part, and it is possible to suppress a concern that a white defect is formed by forming a gap between the correction film and the defect peripheral part. Become. As a result, the defect-corrected area has a gray tone effect almost equal to the transmittance range allowed for the normal gray tone portion in the semi-transparent portion, and is generated in the semi-transparent portion. Defects can be suitably corrected. Furthermore, it is possible to design the correction film in advance to be larger than the white defect portion by utilizing the above effect. This can be particularly suitably applied to a mask with low tolerance for white defects.
Further, according to the gray tone mask manufacturing method of the present invention, the defect generated in the semi-translucent portion is suitably corrected by including the defect correcting step to which the defect correcting method of the present invention is applied. A tone mask can be obtained.

  Further, according to the gray-tone mask of the present invention, the semi-transparent portion is formed of a semi-transparent film, and a predetermined portion of the semi-transparent portion is exposed to a portion on the peripheral side from the central portion rather than the central portion. By forming a correction film having a region with a large amount of light transmission, even when the correction film overlaps the defect peripheral portion, it is possible to suppress a decrease in the light transmission amount of the portion, and the correction film and the defect peripheral edge. It is possible to suppress a concern that a white defect is formed by forming a gap in the portion. As a result, in the region where the defect is corrected, a gray tone effect almost equal to the transmittance range allowed for the normal gray tone portion in the semi-transparent portion is obtained, and the defect generated in the semi-transparent portion is preferable. A gray-tone mask modified in the above is obtained.

The best mode for carrying out the present invention will be described below with reference to the drawings.
[First Embodiment]
FIG. 1 is a cross-sectional view for explaining a pattern transfer method using a gray-tone mask of the present invention. FIG. 2 shows a first embodiment of a defect correction method for a gray-tone mask according to the present invention. (1) is a plan view before defect correction, (2) is a plan view in the middle of correction, (3 ) Is a plan view after defect correction, (4) is a side sectional view taken along line LL in (3), and (5) is a curve diagram showing light transmittance (T) in the section shown in (4). is there.

  The gray-tone mask 20 of the present invention shown in FIG. 1 (the repaired defect area is not shown here) is, for example, a thin film transistor (TFT) or a color filter of a liquid crystal display (LCD) or a plasma display panel (PDP). The resist pattern 33 having different film thicknesses is formed stepwise or continuously on the transfer target 30 shown in FIG. In FIG. 1, reference numerals 32 </ b> A and 32 </ b> B denote films stacked on the substrate 31 in the transfer target 30.

  Specifically, the gray tone mask 20 transmits a light shielding portion 21 that shields exposure light (transmittance is substantially 0%) when the gray tone mask 20 is used, and exposure light with the surface of the transparent substrate 24 exposed. And a semi-translucent portion 23 that reduces the transmittance to 20 to 60%, preferably about 40 to 60% when the exposure light transmittance of the translucent portion is 100%. Composed. The translucent part 23 is configured by forming a translucent semi-transparent film 26 on a transparent substrate 24 such as a glass substrate. The light shielding unit 21 is configured by providing a light shielding film 25 on a transparent substrate 24. Note that the pattern shapes of the light shielding portion 21, the light transmitting portion 22, and the semi-light transmitting portion 23 shown in FIGS. 1 and 2 are merely representative examples, and it is needless to say that the present invention is not limited thereto. It is.

  Examples of the semi-transparent film 26 include chromium compounds, MoSi, Si, W, and Al. Among these, chromium compounds include chromium oxide (CrOx), chromium nitride (CrNx), chromium oxynitride (CrOxN), chromium fluoride (CrFx), and those containing carbon and hydrogen. Examples of the Mo compound include MoSix, MoSi nitride, oxide, oxynitride, and carbide. Examples of the light shielding film 25 include Cr, Si, W, and Al. The transmittance of the light shielding part 21 is set by selecting the film material and the film thickness of the light shielding film 25. Further, the transmittance of the semi-translucent portion 23 is set by selecting the film material and the film thickness of the semi-transparent film 26.

  When the gray tone mask 20 as described above is used, the exposure light is not substantially transmitted through the light shielding portion 21, and the exposure light is reduced at the semi-transparent portion 23. When the resist film (positive type photoresist film) undergoes development after transfer, the film thickness is increased at a portion corresponding to the light-shielding portion 21, and the film thickness is decreased at a portion corresponding to the semi-translucent portion 23. A resist pattern 33 having no film is formed in a portion corresponding to the portion 22 (see FIG. 1). In the resist pattern 33, the effect of reducing the film thickness at the portion corresponding to the semi-transparent portion 23 is called a gray tone effect. In the case of using a negative photoresist, it is necessary to design in consideration that the resist film thickness corresponding to the light shielding portion and the light transmitting portion is reversed. The effect is sufficiently obtained.

  Then, first etching is performed on, for example, the films 32A and 32B in the transfer target 30 at a portion where the resist pattern 33 shown in FIG. 1 is not provided, and the thin portion of the resist pattern 33 is removed by ashing or the like. Then, the second etching is performed on, for example, the film 32 </ b> B in the transfer target 30. In this way, a process for two conventional photomasks is performed using one gray-tone mask 20, and the number of masks is reduced.

Next, the defect correction method according to this embodiment will be described. In this embodiment mode, a light-transmitting film containing molybdenum silicide (exposure light transmittance of 50%) and a light-shielding film containing chromium as a main component are formed on a transparent substrate, and light shielding is performed by performing predetermined patterning. A gray-tone mask for manufacturing a TFT substrate, which includes a portion, a light-transmitting portion, and a semi-light-transmitting portion is used. The manufacturing method will be described later.
A method for correcting a white defect generated in the semi-translucent portion according to the present embodiment will be described with reference to FIG.

(1) About the manufactured gray-tone mask, the defect inspection of a mask pattern is performed using a defect inspection apparatus. And when a defect exists in a semi-translucent part, the positional information and shape information of this defective area are specified. The defect in this case has a part where the thickness of the semi-transparent film is small or the semi-transparent film is missing with respect to the normal semi-transparent part. This is a so-called white defect that is larger than the light part.
As a result of the defect inspection, as shown in FIG. 2 (1), the white defect region 50 was present in the semi-transparent portion 23 made of the semi-transparent film 26. Note that the actual defects generated in the mask are often irregularly shaped, but here, for the sake of convenience, those having an almost elliptical shape are shown.

(2) Next, as a first stage of correction, a correction film is formed in an area smaller than the defective area. First, a film forming means and a film forming material for forming a correction film are determined. In this embodiment mode, an FIB apparatus is used as a film forming unit. Further, as the film forming material, a material containing molybdenum silicide which is the same as that of the semi-transparent film may be used, but it is preferable to use a material which is suitable for film formation by the FIB apparatus and whose light transmission amount can be easily controlled. In this embodiment, carbon is used. Carbon is not only suitable for film formation by an FIB apparatus and easy to control the amount of light transmission, but is also a material excellent in chemical resistance and adhesion strength.

Here, the FIB apparatus will be described. As shown in FIG. 3, the FIB apparatus 40 includes an ion source 41 that generates Ga ⁺ ions, an electromagnetic optical system 42, an electron gun 43 that emits electrons for neutralizing Ga + ions, and β gas. An etching gas gun 49 to be released and a gas gun 44 to release pyrene gas are provided. The electromagnetic optical system 42 uses Ga + ions generated from the ion source 41 as an ion beam 47, and the ion beam 47 is scanned by a scan amplifier 46.
Then, by placing the gray tone mask 20 as the object to be corrected on the XY stage 45 and moving the XY stage 45, the defect area to be corrected in the gray tone mask 20 is moved to the ion beam irradiation area. To do. Next, the ion beam 47 is scanned over the defect area to be corrected, and the position of the defect area to be corrected is detected by the action of the secondary ion detector 48 that detects the secondary ions generated at this time. By irradiating the defect region to which the gray tone mask 20 is corrected through the electromagnetic optical system 42 through the electromagnetic optical system 42, the correction film is formed and the semi-transparent film in the black defect region is removed. The ion beam has a beam diameter of 0.1 μmφ or less.

In the case of forming a correction film, pyrene gas is emitted by the gas gun 44 while the ion beam 47 is emitted through the electromagnetic optical system 42. As a result, the pyrene gas comes into contact with the ion beam 47 and polymerizes (chemical reaction), and a correction film is deposited on the irradiation region of the ion beam 47 to form a film.
Further, when removing the semi-transparent film in the black defect region, β gas is emitted by the etching gas gun 49, and the ion beam 47 is irradiated through the electromagnetic optical system 42 in this state, whereby the above-mentioned half-transmission film is obtained. The translucent film is removed.

As a first-stage correction, a correction film having a higher transmittance than the transmittance (50%) of the semi-transparent film 26 is formed. Here, for example, a correction having a transmittance of 70% is performed. Deposition conditions using an FIB apparatus for forming a film are determined. In the case of film formation using an FIB apparatus, the parameter for controlling the film transmittance is mainly the dose per unit area of the ion beam (Dose, which is proportional to the current value during film formation). In addition, as the film formation region of the first-stage correction film, a region 52 that is smaller than the region within the white defect region 50 is set. The difference in size between the defect area and the film formation area (size margin) is set in consideration of the positioning accuracy of the film formation apparatus (FIB apparatus) and the like, and here, the film formation area is set to have a gap of 1 μm, for example.
As the correction film formation region 52, necessary position information and the like are input to the FIB apparatus, and the above film formation conditions are input to form the correction film 28 in the film formation region 52 (see FIG. 2B). .

(3) Next, as a second stage of correction, a correction film is formed in an area larger than the white defect area. As a film formation region of the second-stage correction film, a region 53 including the white defect region 50 and larger than the region is set. The difference in size between the defect area and the film formation area (size margin) is determined in consideration of the positioning accuracy of the film formation apparatus (FIB apparatus), and the film formation area is set to have a size margin of, for example, 1 μm. .
Necessary position information or the like is input to the FIB apparatus as the correction film formation region 53, and other film formation conditions and film formation materials are set in the film formation region 53 in the same manner as in the first-stage film formation. (See FIGS. 2 (3) and (4)).

  As a result of the above defect correction, as shown in FIG. 2 (5), in the vicinity of the center of the white defect region, the exposure light transmittance is increased by the lamination of the first-stage correction film 28 and the second-stage correction film 29. It was almost 50% (indicated by A in the figure), and had a gray tone effect similar to that of a normal semi-translucent portion. Further, only the correction film 29 having a higher exposure light transmittance than the central portion (the correction film laminated portion) is formed in the peripheral portion of the white defect region, and the semi-transmission having a normal transmittance in a margin region of less than 2 μm. A part slightly higher and a part lower than the part were formed (indicated by B and C in the figure), but under the exposure conditions when using the mask, it was not resolved and the transmittance was within the allowable range. It became usable without problem.

  The method for correcting white defects has been described above. However, when there is a black defect due to adhesion of a light-shielding film component or the like in the semi-transparent portion, an attempt is made to remove only the black defect using an FIB apparatus or the like. Further, it is difficult to remove the black defect without affecting the semi-transparent film. Therefore, in the case of a black defect, the semi-transparent film in the region including the black defect is removed by an FIB apparatus, a laser, or the like, and the removed region is used as a defect region and the same correction as in the case of the above-described white defect is performed. In addition, the correction can be suitably performed.

  As described above, according to the present embodiment, the correction film formed in the region including the defective region has a region where the amount of exposure light transmitted is larger than that in the central portion in the peripheral portion of the correction film. As a result, the reduction in light transmission at the portion where the correction film overlaps the defect peripheral portion can be reduced, and there is no gap between the correction film and the defect peripheral portion. A gray tone effect equivalent to that of the tone portion can be obtained, and defects generated in the semi-transparent portion can be suitably corrected.

In the present embodiment, the same film formation conditions are applied in the process of forming the correction film twice, but an exposure light transmittance of, for example, about 50% can be obtained as a result of the lamination by the film formation twice. If the conditions are satisfied, different film forming conditions may be applied, and if the same conditions are satisfied, three or more film forming steps may be performed. Further, the order of the step of forming the correction film in the region smaller than the defect region and the step of forming the correction film in the region larger than the defect region may be reversed. That is, first, a correction film may be formed in an area larger than the defect area, and a correction film may be formed thereon in an area smaller than the defect area.
In this embodiment, the FIB apparatus is applied as the correction film forming means. However, the film forming means is not limited to the FIB apparatus, and other film forming means such as laser CVD is applied. It is also possible.
Furthermore, in the present embodiment, the central portion of the correction film is set to a transmittance that is substantially the same as the predetermined exposure light transmittance designated for the semi-transparent portion having no defect, but a mask having a high tolerance for white defects. If so, the exposure light transmittance higher than the predetermined exposure light transmittance can be set. On the contrary, if the mask has a large tolerance for black defects, the exposure is lower than the predetermined exposure light transmittance. The light transmittance can also be set. The same applies to the following embodiments.

[Second Embodiment]
4A and 4B show a second embodiment of a defect correction method for a gray-tone mask according to the present invention. FIG. 4A is a plan view before defect correction, FIG. 4B is a plan view after defect correction, 3) is a side sectional view taken along line LL in (2), and (4) is a curve diagram showing light transmittance (T) in the section shown in (3).
A method for correcting a white defect generated in a semi-translucent portion according to the present embodiment will be described with reference to FIG.

(1) As in the first embodiment, the manufactured gray-tone mask is subjected to a mask pattern defect inspection using a defect inspection apparatus, and when a defect exists in the semi-translucent portion, the defect region Specify position information and shape information. As a result of the defect inspection, as shown in FIG. 4 (1), the white defect region 50 was present in the semi-transparent portion 23 made of the semi-transparent film 26.

(2) Next, a correction film is formed in an area larger than the defect area. As the film forming means for forming the correction film, the FIB apparatus is applied as in the first embodiment, and the film forming material is carbon.
In the correction according to the present embodiment, when the correction film is formed by the FIB apparatus, the focus is offset by a predetermined amount (for example, 1 μm) in consideration of the accuracy of the film formation apparatus, and the ion beam is moved more than the just focus position. Irradiate in a focused state, the deposition amount should be reduced in the peripheral portion from the center of the correction film, and the exposure light transmittance should be increased by that amount, and the defect area Film formation is performed so that the exposure light transmittance at the same level as that of a normal semi-transparent portion is satisfied in the central portion. The blurring area (width) due to defocus cannot be unequivocally explained by the transmittance of the semi-translucent portion, the transmittance distribution due to defocus, the process margin, etc. It is preferable to do this.

In the present embodiment, as the film formation region of the correction film, the region 51 including the white defect region 50 and larger than the region is set. The difference in size between the defect area and the film formation area (size margin) is determined in consideration of the positioning accuracy of the film formation apparatus (FIB apparatus), and the film formation area is set to have a size margin of, for example, 1 μm. .
As the correction film forming region 51, necessary position information and the like are input to the FIB apparatus, and the necessary film forming conditions are input to form the correction film 27 in the film forming region 51 (FIG. 4B). (Refer to (3)).

As a result of the above defect correction, as shown in FIG. 4 (4), the transmittance of the exposure light is almost 50% (indicated by A in the figure) near the center of the white defect region, and a normal semi-transparent portion. And had the same gray tone effect. In addition, a correction film 27 having a larger exposure light transmittance than the central portion is formed in the peripheral portion of the white defect region, and a slightly higher portion and a slightly higher transmittance than the normal semi-transparent portion in the blur region less than 2 μm. Low part was formed (indicated by B and C in the figure), but under the exposure conditions when using the mask, it was not resolved and the transmittance was within the allowable range. became.
The method for correcting white defects according to the present embodiment has been described above. However, in the case of a black defect, the semi-transparent film in the region is removed and the same correction as in the case of the white defect described above is performed. In this case, the correction can be suitably performed.

  As described above, also in the present embodiment, the correction film formed in the region including the defect region has a region where the amount of exposure light transmitted is larger in the peripheral portion than in the central portion. Because the reduction in light transmission at the part where the correction film overlaps the defect peripheral part can be reduced, and there is no gap between the correction film and the defect peripheral part, the area where the defect has been corrected is a normal gray tone in the semi-transparent part. A gray tone effect equivalent to that of the portion can be obtained, and defects generated in the semi-transparent portion can be suitably corrected.

Next, an example of a manufacturing method of the gray tone mask used in the above-described embodiment will be described with reference to FIG.
In the mask blank to be used, a light shielding film 25 is formed on a transparent substrate 24 (see FIG. 10A). The material of the light shielding film 25 is a composite film of Cr and its compound.
First, a resist is applied on the light shielding film 25 of the mask blank to form a resist film. For drawing, an electron beam or light (short wavelength light) is usually used in many cases, but in this embodiment, laser light is used. Therefore, a positive photoresist is used as the resist. Then, a predetermined pattern (a pattern that forms a resist pattern corresponding to the light shielding portion) is drawn on the resist film, and development is performed after the drawing, thereby forming a resist pattern 80 corresponding to the light shielding portion (see FIG. 10 (b)).

Next, the light shielding film 25 is etched using the resist pattern 80 as an etching mask to form a light shielding film pattern. In this embodiment, since a composite film of Cr and its compound is used as the light shielding film, either dry etching or wet etching can be used as the etching means. In this embodiment, wet etching was used.
After the remaining resist pattern is removed (see FIG. 10C), a semi-transmissive film 26 is formed on the entire surface of the substrate (see FIG. 10D). The semi-transparent film 26 has a transmission amount of about 50 to 20% with respect to the transmission amount of the exposure light of the transparent substrate 24. In this embodiment, the semi-transparent film 26 is made of a semi-transparent Cr oxide (transmittance of 50%). The light-transmitting film 26 was used.

Next, the same resist film as described above is formed on the semi-transparent film 26, and a second drawing is performed. In the second drawing, a predetermined pattern is drawn so as to form a resist pattern corresponding to the semi-translucent portion (a resist pattern is formed on the semi-translucent portion). After drawing, development is performed to form a resist pattern 81 in a region corresponding to the semi-translucent portion (see FIG. 10E).
Then, the exposed semi-transparent film 26 is etched using the resist pattern 81 as an etching mask to form a semi-transparent film pattern constituting the semi-transparent portion. In this embodiment, dry etching that provides high etching selectivity between the semi-transparent film 26 and the light shielding film 25 is used as the etching means in this case.
Then, the remaining resist pattern is removed, and the gray tone mask 20 is completed (see FIG. 10F).

  In addition, the manufacturing method of the gray tone mask of this invention is not limited to the said Example. In the above embodiment, a mask blank having a light shielding film formed on a transparent substrate was used, and a semi-transparent film was formed in the middle of the manufacturing process. For example, the semi-transparent film and the light shielding film were formed on the transparent substrate. It is also possible to manufacture using a mask blank formed in order. In this case, the light shielding portion is formed of a laminated film of a semi-transparent film and a light shielding film.

It is sectional drawing for demonstrating the pattern transfer method using the gray tone mask of this invention. 1 shows a first embodiment of a defect correction method for a gray-tone mask according to the present invention, where (1) is a plan view before defect correction, (2) is a plan view in the middle of correction, and (3) is defect correction. The following plan view, (4) is a side sectional view, and (5) is a curve diagram showing the light transmittance (T) in the section. It is a schematic side view which shows the structure of a FIB apparatus. 2 shows a second embodiment of a defect correction method for a gray-tone mask according to the present invention, where (1) is a plan view before defect correction, (2) is a plan view after defect correction, and (3) is a side view. Sectional drawing, (4) is a curve diagram showing the light transmittance (T) in the section. It is a schematic sectional drawing which shows the manufacturing process of the TFT substrate using a gray tone mask. It is a schematic sectional drawing which shows the manufacturing process (continuation of the manufacturing process of FIG. 5) of the TFT substrate using a gray tone mask. It is a top view which shows an example of the conventional fine pattern type gray tone mask. It is a top view for demonstrating the ideal defect correction method. It is a figure for demonstrating the problem in the conventional defect correction method. It is sectional drawing which shows an example of the manufacturing process of the gray tone mask of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10,20 Gray tone mask 21 Light-shielding part 22 Light-transmitting part 23 Semi-light-transmitting part 24 Transparent substrate 25 Light-shielding film 26 Semi-light-transmitting film 27 Correction film 30 Transfer object 33 Resist pattern 40 FIB apparatus 50 Defect area

Claims (16)

A resist pattern having a light-shielding portion, a light-transmitting portion, and a semi-light-transmitting portion that reduces a transmission amount of exposure light used when using a mask by a predetermined amount, and having different film thicknesses stepwise or continuously on a transfer target A gray-tone mask defect correcting method for forming
The semi-transparent portion is formed of a semi-transparent film;
Identifying a defect region in the semi-translucent portion;
Forming a correction film in a region including the defect region,
2. The gray tone mask defect correcting method according to claim 1, wherein the correction film has an area where the amount of exposure light transmitted is larger than that of the central portion at a portion on the peripheral side of the central portion.   2. The gray tone mask defect correcting method according to claim 1, wherein the amount of exposure light increases continuously or stepwise from the central portion toward the peripheral portion of the correction film.   2. The gray tone mask defect correcting method according to claim 1, wherein the correction film has a region having a film thickness smaller than that of the central portion at a peripheral portion of the correction film.   4. The gray tone mask defect correcting method according to claim 3, wherein the thickness of the correction film decreases continuously or stepwise from the center to the periphery.   Since the defect region has a portion where the thickness of the semi-transparent film is small or the semi-transparent film is missing with respect to the normal semi-transparent portion, the amount of exposure light transmitted is normal. 5. The gray-tone mask defect correcting method according to claim 1, wherein the region is larger than the area.   The defect region is a semi-transparent portion where the amount of exposure light is normal because the film thickness of the semi-transparent film is large or components other than the semi-transparent film are attached to the normal semi-transparent portion. 5. The gray-tone mask defect correcting method according to claim 1, wherein the area is a smaller area.   The correction film forming step includes two or more film forming steps, and in each film forming step, the semi-transparent portion has a transmission amount larger than the transmission amount of exposure light that gives a desired gray tone effect. 7. The gray tone mask defect correcting method according to claim 1, wherein a translucent film is formed.   The two or more film forming steps of the correction film include a step of forming a film in a region smaller than the defect region in the defect region, and a step of forming a film in a region including the defect region and larger than the defect region. The defect correcting method for a gray tone mask according to claim 7.   9. The gray tone mask defect correction method according to claim 1, wherein a focused ion beam method is applied to the correction film forming step.   10. The gray-tone mask defect correcting method according to claim 9, wherein the ion beam is irradiated in a defocused state.   A method for manufacturing a gray-tone mask, comprising a defect correcting step by the defect correcting method according to claim 1. A resist pattern having a light-shielding portion, a light-transmitting portion, and a semi-light-transmitting portion that reduces a transmission amount of exposure light used when using a mask by a predetermined amount, and having different film thicknesses stepwise or continuously on a transfer target A gray tone mask for forming
The semi-transparent part is formed of a semi-transparent film, and the predetermined part of the semi-transparent film has a region where the amount of exposure light transmitted is larger than that of the central part at a peripheral side of the central part. A gray-tone mask, wherein a correction film is formed.   The gray-tone mask according to claim 12, wherein the correction film has a large amount of exposure light transmitted continuously or stepwise from the center to the periphery.   The gray-tone mask according to claim 12, wherein the correction film has a region having a thickness smaller than that of the central portion in a portion on a peripheral side of the central portion.   15. The gray tone mask according to claim 14, wherein the thickness of the correction film decreases continuously or stepwise from the center to the periphery. The gray-tone mask according to the manufacturing method according to claim 11 or the gray-tone mask according to any one of claims 12 to 15 and an exposure machine, and a pattern formed on the gray-tone mask is applied to a transfer object. A pattern transfer method characterized by transferring.

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