JP4249509B2 - Phase shift reticle manufacturing method and phase shifter defect correcting method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a photomask used for manufacturing a semiconductor device, and more particularly to a method for manufacturing a phase shift reticle and a method for correcting a defect of a phase shifter for forming a fine pattern on a wafer with high density. .
[0002]
[Prior art]
As semiconductor integrated circuit elements are miniaturized, the phase shift exposure method using a phase shift reticle (also referred to as a phase shift mask or a phase shift photomask) is widely used as the exposure wavelength in the lithography process becomes shorter. It has become to. The phase shift reticle is provided with a phase shifter, which utilizes the interference between the light whose phase has changed through the phase shifter and the light whose phase has not changed without passing through the phase shifter at the time of transfer exposure to the wafer. , Resolution can be improved. The basic idea and principle regarding the phase shift reticle have already been described in prior art documents (for example, see Patent Document 1 and Patent Document 2).
The exposure method using the phase shift reticle can increase the resolution of the device pattern transferred from the reticle to the wafer by changing the mask from the conventional reticle to the phase shift reticle even when the same projection exposure apparatus is used. At the same time, it has a great feature that the depth of focus can be increased.
[0003]
There are various types of phase shift reticles such as a Levenson type, a halftone type, and an auxiliary pattern type, and in each type, a structure in which a phase shifter is provided above a transparent substrate such as a synthetic quartz glass through a light shielding film pattern ( And a structure (substrate digging type) that forms a phase shifter by digging a transparent substrate by etching.
[0004]
For example, in the conventional method for producing a shifter-mounted phase shift reticle, when the phase shifter film is formed by spin coating, the surface state of the mask substrate is partially poor when the viscosity of the phase shifter material is low, When the phase shifter material is repelled in that portion, the formed phase shift film 93 becomes as shown in FIG. When this phase shift film 93 is patterned to form a phase shifter, as shown in FIG. 9B, a pinhole defect 95 is generated in the phase shifter 96, and when the foreign material is mixed in the shifter material or on the substrate. When foreign matter is present, the phase shifter 96 has a defect 94 due to the mixed foreign matter, an uneven defect on the surface of the phase shifter film, a step defect 97 due to a pattern step such as a light shielding film formed on the lower layer substrate of the phase shifter. End up.
In addition, even when a phase shift film is formed by vacuum deposition such as vapor deposition or sputtering, pinhole defects or step defects in the phase shifter and foreign matters mixed into the phase shifter film due to the surface condition of the mask substrate or foreign matter contamination. Caused a defect.
[0005]
In phase shift exposure, the phase shift reticle manufacturing method and phase shifter defect correction are more defective because defects of the phase shifter are transferred onto the wafer even smaller defects than conventional chrome pattern defects. Therefore, a manufacturing method that eliminates this problem and a more accurate defect correction technique are required.
Therefore, conventionally, as shown in FIG. 10, for example, a method of correcting the remaining defect (convex defect) 104 of the phase shifter with a shifter-mounted structure by introducing an assist gas 106 into the focused ion beam apparatus, or a halftone phase shift A method of correcting the remaining defect (convex defect) of the mask by flying with a laser, or correction of the pinhole defect 105 by film deposition of the carbon deposition method 107 using a focused ion beam as shown in FIG. It was.
Further, a method has been proposed in which defects due to a step in the thickness of the phase shifter due to a step in the lower layer pattern are removed by planarization using CMP (see, for example, Patent Document 3).
[0006]
Further, as a method for correcting a phase shifter defect such as a pinhole defect, a method for correcting the phase shifter defect by filling the pinhole defect with a defect correction material and etching back has been proposed (for example, Patent Document 4, Patent). Reference 5 and Patent Document 6).
[0007]
However, in these conventional defect correction methods, since the correction method differs depending on the defect, it is necessary to detect the location of the defect and determine the type of the defect, and also to correct only the phase shifter surface state. There has been a problem that it is impossible to correct a defect caused by foreign matters mixed in the phase shifter film during the formation.
[0008]
[Patent Document 1]
Japanese Patent Publication No.58-173744
[Patent Document 2]
Japanese Examined Patent Publication No. 62-59296
[Patent Document 3]
JP-A-7-261369
[Patent Document 4]
JP-A-5-142757
[Patent Document 5]
JP-A-6-75362
[Patent Document 6]
JP-A-7-146544
[0009]
[Problems to be solved by the invention]
Accordingly, the present invention has been made to solve such problems. Its purpose is to provide a phase shift reticle manufacturing method that eliminates the occurrence of phase shifter defects as much as possible, and a phase shift reticle phase shifter defect correction method that can be corrected in an easy process regardless of the type of phase shifter defect. Is to provide.
[0010]
[Means for Solving the Problems]
In order to solve the above-described problem, a phase shift reticle manufacturing method according to the invention of claim 1 includes a step of forming a first phase shift film on a substrate in the phase shift reticle manufacturing method, and the phase shift reticle. A step of polishing the surface of the film to planarize the film and discharge foreign matter in the film; and a second phase shift film having optical properties similar to those of the first phase shift film on the polished phase shift film. Forming and filling the pinhole defect of the first phase shift film, polishing the surface of the second phase shift film, and adding the first phase shift film and the second phase shift film together The phase shift film is patterned to form a phase shifter, and the phase difference of the exposure light when using the phase shift reticle of the phase shift film obtained by adding the first phase shift film and the second phase shift film Is 1 In which was set to 0 degrees. According to the present invention, the final phase shift film is formed with most of the defects removed as described above, and the phase shift film is patterned to form a phase shifter, thereby eliminating the shifter defects as much as possible. A phase shift reticle is provided.
[0011]
According to a second aspect of the present invention, there is provided a phase shift reticle manufacturing method comprising the steps of: forming a first phase shift film on a substrate; and polishing the surface of the phase shift film to planarize the film. And a step of discharging foreign matter in the film, and forming a second phase shift film having optical properties similar to those of the first phase shift film on the polished phase shift film, and the first phase shift A step of filling pinhole defects in the film, a step of polishing the surface of the second phase shift film, and optical properties similar to those of the first phase shift film on the surface-polished second phase shift film. A step of forming a phase shift film that is laminated by repeating a cycle of polishing the surface, and a step of patterning the laminated phase shift film to form a phase shifter, Serial phase difference between exposure light during phase shift reticles used in laminated phase shift film is obtained as 180 degrees. According to the present invention, there is provided a phase shift reticle that is extremely unlikely to have a shifter defect such as a pinhole defect.
[0012]
According to a third aspect of the present invention, there is provided a phase shift reticle manufacturing method in which the first phase shift film is formed on the substrate and the surface is polished, and the phase difference of the exposure light when using the phase shift reticle is 180 degrees or 180 degrees. The phase shift film is ground to such a thickness that it becomes smaller. According to the present invention, in the phase shift film forming step, in the surface polishing step of the first phase shift film, the film is ground to a thickness necessary for reversing the phase of the exposure light or a thickness smaller than the film thickness. As a result, defects due to surface irregularities and steps are removed, and a phase shift reticle having a phase shifter in which foreign matter inside the film is sufficiently removed is provided.
[0013]
A phase shift reticle phase shifter defect correcting method according to a fourth aspect of the invention is the phase shift reticle phase shifter defect correcting method, wherein the phase shift reticle is cleaned and dried, and then the phase shifter is subjected to surface polishing. Forming a phase shift film showing the same optical properties over the entire surface, surface polishing and flattening to fill pinhole defects, and patterning the phase shift film to form a phase shifter, The phase shifter is such that the phase difference of the exposure light when using the phase shift reticle is 180 degrees.
[0014]
A phase shifter defect correcting method for a phase shift reticle according to a fifth aspect of the present invention has the same optical properties as those of the phase shift film after the step of planarizing the phase shift film and filling the pinhole defects in the surface polishing process. And a step of polishing the surface and patterning the phase shift film to form a phase shifter. The phase shifter has a phase difference of exposure light when using a phase shift reticle. The angle is set to 180 degrees.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below.
(Phase shift reticle manufacturing method)
In the method for producing a phase shift reticle of the present invention, as a substrate for forming a phase shifter, a transparent substrate such as a quartz substrate usually used for a photomask or a light shielding film pattern such as chromium is formed in advance on a transparent substrate such as a quartz substrate. A photomask is used.
[0016]
As a first embodiment of the method for producing a phase shift reticle of the present invention, a method for forming a phase shift film comprises a combination of two phase shift film forming steps and two phase shift film surface polishing steps. It is what.
If the phase shift film formed in the step of forming the first phase shift film has a pinhole defect, a convex defect, a shifter film thickness step defect or a foreign substance defect in the film, the phase shift film By performing the surface polishing process, convex defects and level differences in the shifter film thickness are removed by flattening, and foreign matter defects in the film are removed and removed from the film during planarization, and foreign matter enters. In the phase shift film after the surface polishing process, only the pinhole defect exists.
The pinhole defect is filled by performing a step of forming a second phase shift film having the same optical characteristics as the first phase shift film on the phase shift film in which only the pinhole defect exists. Thus, defects are removed, and a phase shift film having a predetermined film thickness without defects is obtained by a step of grinding and removing the second phase shift film from which all the defects have been removed to a required film thickness by surface polishing.
Subsequently, a phase shift reticle provided with a phase shifter is completed by patterning the phase shift film.
[0017]
In the second phase shift film forming step of the present invention described above, there may be pinhole defects, convex defects, foreign matter defects in the film, etc. in the second film. When the shift film is ground to the required film thickness in the surface polishing step, the convex defects are flattened, and the foreign matter defects in the film are discharged to the outside. Since only pinhole defects are present, the probability that the pinhole defects of the second phase shift film overlap with the pinhole defects present in the first phase shift film as the lower layer is considered to be very low. The probability of a serious pinhole defect can be kept low.
[0018]
The surface polishing method used in the present invention is preferably a polishing method using a CMP (Chemical Mechanical Polishing) apparatus. By monitoring the change in torque of the rotary drive unit by a method of monitoring electric capacity, the end point of polishing can be detected. The thickness of the phase shift film can be controlled with high accuracy, and flattening polishing without generation of particles is possible.
[0019]
In the phase shift film forming step, in the surface polishing step of the second phase shift film formed to fill the pinhole defect of the first phase shift film, the first phase shift film and the second phase shift film The added phase shift film is ground so that the phase of the exposure light at the time of exposure using the reticle is 180 degrees, so that defects are eliminated as much as possible. A phase shift film having an optical property that reverses the phase of light can be obtained.
[0020]
In order to obtain high resolution in transfer exposure on a wafer using a phase shift reticle, the phase of exposure light that passes through an opening with a phase shifter and exposure light that passes through an opening without a phase shifter Therefore, it is necessary to control the phase change amount of the phase shift film so as to be inverted, and this phase change amount becomes φ (radian) expressed by the following equation (1).
φ = 2π (n−1) d / λ (1)
Here, n is the refractive index in the exposure region of the material forming the phase shift film, d is the thickness of the phase shift film, and λ is the wavelength of the exposure light. That is, since the film thickness of the phase shift film is determined by the wavelength of the exposure light and the refractive index of the phase shift film material, the control of the film thickness of the phase shift film is important for controlling the phase angle.
Here, when the exposure light is i-line (wavelength 365 nm) and the phase shift film material is silicon dioxide (refractive index is about 1.5), the film thickness required to reverse the phase by 180 degrees is less than 400 nm. Therefore, in the phase shift film forming process of the present invention, the first phase shift film is preferably ground to a film thickness of 400 nm or less in the surface polishing process.
[0021]
The second embodiment of the method for producing a phase shift reticle of the present invention comprises a step of repeating a combination of two or more phase shift film forming steps and two or more phase shift film surface polishing steps, and comprises surface polishing. A third and subsequent phase shift films may be further formed on the second phase shift film, if necessary, and the third and subsequent phase shift films may be polished. When the above repeating steps are repeated, the film thickness stacked by the cycle of each film forming step and polishing step can be reduced.
Also, in this case, each phase shift film thickness is set in advance so that the phase shift film formed in the last film forming process is used only for pinhole defect embedding, and the last phase shift film is set to the film thickness. If the film is completely removed, this film is used only to fill in pinhole defects existing in the film below the film, so that the possibility of remaining pinhole defects can be extremely reduced.
[0022]
In the present invention, as a material of the phase shift film, when a Levenson type phase shifter is formed, for example, a film obtained by applying and baking SOG (Spin On Glass) which is a coating type silicon oxide is used. Further, when forming a halftone phase shifter, it has a predetermined transmittance for exposure light, for example, Si oxide film, Si nitride film, Si oxynitride film, MoSi oxynitride film, A film formed by vacuum-forming a W oxynitride film, a TaSi oxynitride film, a Cr oxynitride film, a Cr oxynitride carbon film, a Cr fluoride film, or the like is used. The second phase shift film or the phase shift film to be further stacked may have the same optical properties as the first phase shift film in terms of refractive index, transmittance, etc., and is not limited to the material of each phase shift film. However, the same material is more preferable.
[0023]
(Phase shifter defect correction method)
In the phase shifter defect correcting method of the phase shift reticle of the present invention, the method of correcting the phase shifter comprises a combination of a phase shift film forming step described below and two phase shift film surface polishing steps, and the correction is performed as described above. This is a method of correcting defects without patterning the phase shift film without affecting the lower layer of the phase shifter.
If there are pinhole defects, convex defects, shifter film thickness step defects, foreign matter defects in the film, etc. in the phase shifter of the phase shift reticle, after cleaning and drying the phase shift reticle, By performing the surface polishing process of the phase shifter, convex defects and steps in the shifter film thickness are removed by flattening, and foreign matters in the phase shifter are discharged and removed outside during the flattening, and foreign matters are removed. The place where it has entered becomes a pinhole defect, and only the pinhole defect is present in the phase shifter after the surface polishing process.
By performing a step of forming a second phase shift film having the same optical properties as the phase shifter on the phase shifter in which only the pinhole defect exists, the defect is filled with the pinhole defect. By removing the second phase shift film from which all defects have been removed by grinding to the required film thickness by surface polishing, a phase shift film having a predetermined film thickness without defects can be obtained.
Subsequently, a phase shift reticle provided with a phase shifter modified by patterning the phase shift film is completed.
[0024]
In the phase shift reticle shifter defect correcting method of the present invention, the method of correcting the phase shifter is a combination of one or more phase shift film forming steps and two or more phase shift film surface polishing steps, which is necessary. In response to this, the third and subsequent phase shift films may be further formed, and the third and subsequent phase shift films may be repeatedly polished. In this case, the film thickness stacked by the cycle of each film forming process and polishing process can be reduced.
In the above case, each phase shift film thickness is set in advance so that the phase shift film formed in the last film formation process is used only for pinhole defect embedding, and the last phase shift film is used as the film. If the film is completely removed by the thickness, this film is used only for filling the pinhole defects existing in the film below the film, so that the possibility of remaining pinhole defects can be extremely reduced.
[0025]
Hereinafter, embodiments of the present invention will be described based on examples with reference to the drawings.
【Example】
Example 1
FIG. 1 and subsequent FIG. 2 are schematic cross-sectional views showing a manufacturing process of a Levenson type phase shift reticle placed on a shifter according to the present invention.
A light-shielding film pattern 12 having a two-layer structure of an 80 nm thick chromium thin film and a 40 nm low reflection chromium thin film provided on an optically polished 6 inch square, 0.25 inch thick synthetic quartz glass substrate 11 The mask (FIG. 1 (a)) is washed and dried to clean the surface, and then the entire surface on the light shielding film pattern surface side is a commercially available coated glass (spin-on glass; SOG), Acuglass 211S manufactured by Allied Signal. Was applied by spin coating and baked at 300 ° C. for 1 hour in a nitrogen atmosphere to obtain an SOG film having a film thickness after baking of about 800 nm. This SOG film was used as the first phase shift film 13 (FIG. 1). (B)).
The first phase shift film 13 includes various defects such as a foreign matter defect 13a, a pinhole defect 13b, and a surface step defect 13c by an appearance inspection using a scanning electron microscope (S6280T manufactured by Hitachi, Ltd.). It was confirmed that
[0026]
Next, a flattened first phase shift film 13 ′ having a thickness of about 400 nm was obtained by grinding by flattening polishing using a CMP apparatus SPP600S manufactured by Okamoto Machine Tool Co., Ltd. (FIG. 1C). In the flattening step, the level difference of the film disappears due to the flattening of the surface, and foreign matter in the film is discharged to the outside, so that only the pinhole defect 14 can be confirmed in the flattened first phase shift film 13 ′. It was.
[0027]
Next, Acuglass 211S manufactured by Allied Signal, which is a commercially available coating glass (spin-on glass; SOG), is applied to the entire surface of the flattened first phase shift film 13 ′ by a spin coating method, and is 300 ° C. in a nitrogen atmosphere. Was fired for 1 hour to obtain an SOG film having a film thickness of about 400 nm after firing, and this SOG film was used as the second phase shift film 15 (FIG. 1D).
[0028]
Next, the second phase shift film 15 is ground by the planarization polishing of the CMP apparatus SPP600S manufactured by Okamoto Machine Tool Manufacturing Co., Ltd., and the first phase shift film 13 ′ having a thickness of about 400 nm and the surface thereof are polished. A phase shift film 16 composed of two phase shift films 15 ′ was obtained (FIG. 1E). The thickness of the phase shift film 16 was set so that the phase difference of the exposure light of the phase shift film obtained by adding the first and second films was 180 degrees when the phase shift reticle was used.
The pinhole defect of the planarized first phase shift film is buried by the formation of the second phase shift film, and in the surface polishing process of the second phase shift film, the level difference of the film disappears due to the planarization of the surface, Since the foreign matter in the film was discharged to the outside, the defect of the obtained phase shift film 16 could not be confirmed.
[0029]
Next, a positive i-line resist (THMR-iP3500, manufactured by Tokyo Ohka Kogyo Co., Ltd.) is spin-coated on the phase shift film, a resist film 17 is formed by baking, and a laser exposure apparatus (E-TEC Co., Ltd.) is then formed according to a conventional method. The phase shift pattern was exposed 18 by using ALTA-3000 (FIG. 2 (f)).
Subsequently, development was performed with an alkaline aqueous solution containing tetramethylammonium hydroxide as a main component, followed by rinsing with pure water to form a phase shifter resist pattern 17 '(FIG. 2 (g)).
[0030]
Next, the phase shift film 16 exposed from the opening of the phase shifter resist pattern 17 ′ is dry-etched with a carbon fluoride gas by a dry etching apparatus (MEPS-6025 manufactured by ULVAC-deposition Co., Ltd.). A pattern of the shifter 16 ′ was formed (FIG. 2 (h)).
Subsequently, the remaining resist was removed by ashing with oxygen plasma to complete the phase shift reticle 10 provided with the defect-free phase shifter 16 '(FIG. 2 (i)).
[0031]
(Example 2)
FIG. 2 and subsequent FIG. 3 are cross-sectional schematic views showing the manufacturing process of the halftone phase shift reticle in the present invention. A first phase shift film 33 is formed by a halftone film in which a chromium oxynitride carbide film having a thickness of 200 nm is formed on an optically polished synthetic quartz glass substrate 31 having a thickness of 6 inches and a thickness of 0.25 inches by a sputtering method. Was formed (FIG. 3A).
The first phase shift film 33 contains various defects such as foreign matter defects 33a, pinhole defects 33b, and surface irregularities by visual inspection using a scanning electron microscope (S6280T manufactured by Hitachi, Ltd.). Was confirmed.
[0032]
Next, a planarized first phase shift film 33 ′ having a thickness of about 130 nm was obtained by grinding by planarization polishing using a CMP apparatus SPP600S manufactured by Okamoto Machine Tool Works (FIG. 3B). In the flattening step, the level difference of the film disappears due to the flattening of the surface, and foreign matter in the film is discharged to the outside, so that only the pinhole defect 34 can be confirmed in the flattened first phase shift film 33 ′. It was.
[0033]
Next, a chromium oxynitride / carbide film having a thickness of 200 nm is formed on the entire surface of the planarized first phase shift film 33 ′ by sputtering, and this halftone film is used as the second phase shift film 35 ( FIG. 3 (c)).
[0034]
Next, a halftone film comprising a first phase shift film having a thickness of about 130 nm and a second phase shift film having a surface polished by grinding by flattening polishing using a CMP apparatus SPP600S manufactured by Okamoto Machine Tool Co., Ltd. Thus, a phase shift film 36 was obtained (FIG. 3D). The thickness of the phase shift film 36 was set so that the phase difference of the exposure light of the phase shift film obtained by adding the first and second films was 180 degrees when the phase shift reticle was used.
The pinhole defect of the planarized first phase shift film is buried by the formation of the second phase shift film, and in the surface polishing step of the second phase shift film, the unevenness of the film is eliminated by the planarization of the surface, Since the foreign matter in the film was discharged to the outside, a defect of the phase shift film 36 due to the obtained halftone film could not be confirmed.
[0035]
Next, a positive electron beam resist (CAP209, Tokyo Ohka Kogyo Co., Ltd.) is spin-coated on the phase shift film 36, a resist film 37 is formed by baking, and then an electron beam exposure apparatus (Hitachi Co., Ltd.) according to a conventional method. The phase shift pattern exposure 38 was performed by a manufacturing company HL-800M (FIG. 4E). Subsequently, after baking at 130 ° C. for 20 minutes, the resist pattern 37 ′ was formed by developing with an alkaline aqueous solution mainly composed of tetramethylammonium hydroxide and rinsing with pure water (FIG. 4 (f)).
[0036]
Next, the phase shift film 36 exposed from the opening of the resist pattern 37 ′ is dry-etched with a halogen-based gas using a dry etching apparatus (MEPS-6025 manufactured by ULVAC-deposition Co., Ltd.), and a phase shifter using a halftone film A pattern 36 ′ was formed (FIG. 4G).
Subsequently, the remaining resist was removed by ashing with oxygen plasma to complete a halftone phase shift reticle 30 provided with a defect-free halftone phase shifter 36 '(FIG. 4 (h)).
[0037]
(Example 3)
FIG. 5 and subsequent FIG. 6 are cross-sectional schematic views showing a manufacturing process of a halftone phase shift reticle as another embodiment of the present invention.
A TaCr transmittance adjusting film 52 having a thickness of 15 nm is formed on an optically polished 6-inch square synthetic glass substrate 51 having a thickness of 0.25 inch by sputtering, and TaSi is oxidized as a phase adjusting film. A film was formed by a 60 nm sputtering method to form a first phase shift film 53 (FIG. 5A).
In the first phase shift film 53, various defects such as foreign matter defects 53a, pinhole defects 53b, and surface irregularities are mixed by appearance inspection using a scanning electron microscope (S6280T manufactured by Hitachi, Ltd.). Was confirmed.
[0038]
Next, a flat first phase shift film 53 ′ having a thickness of about 40 nm was obtained by grinding by planarization polishing using a CMP apparatus SPP600S manufactured by Okamoto Machine Tool Works (FIG. 5B). In the flattening step, the level difference of the film disappears due to the flattening of the surface, and the foreign matter in the film is discharged to the outside. Therefore, only the pinhole defect 54 can be confirmed in the flattened first phase shift film 53 ′. It was.
[0039]
Next, a TaSi oxide film as a phase adjustment film is formed to a thickness of 60 nm on the flattened first phase shift film 53 ′ to form a second phase shift film 55 (FIG. 5C). . Next, a surface-polished second phase shift film 55 ′ having a thickness of about 40 nm was obtained by planarization polishing using a CMP apparatus SPP600S manufactured by Okamoto Machine Tool Works (FIG. 5D). Next, a TaSi oxide film as a phase adjustment film is formed to a thickness of 60 nm on the surface-polished second phase shift film 55 ′ to form a third phase shift film 57 (FIG. 5E). . Next, a third phase shift film 57 ′ having a thickness of about 40 nm was obtained by grinding by flattening using a CMP apparatus SPP600S manufactured by Okamoto Machine Tool Works (FIG. 6F).
[0040]
Next, Acuglass 211S manufactured by Allied Signal, which is a commercially available coated glass (spin-on glass; SOG), is applied to the entire surface of the third phase shift film 57 ′ whose surface has been polished by spin coating, and is 300 ° C. in a nitrogen atmosphere. Was fired for 1 hour to obtain an SOG film having a thickness of about 100 nm after firing, and this SOG film was used as a fourth phase shift film 58 (FIG. 6G).
[0041]
Next, since the 100 nm grinding was performed by the flattening polishing of the CMP apparatus SPP600S manufactured by Okamoto Machine Tool Manufacturing Co., Ltd., the fourth film was used only for embedding pinhole defects in the third film, and the thickness was about 120 nm. The phase-shifted film 56 composed of the first to fourth phase-shifted films is obtained by polishing the surface, and a defect-free halftone film composed of the transmittance adjusting film 52 and the phase-shifted film 56 is formed on the transparent substrate 51. (FIG. 6 (h)).
[0042]
Next, a patterning process of the halftone film will be described (not shown).
A positive-type electron beam resist (Tokyo Ohka Kogyo Co., Ltd. CAP209) is spin-coated on the halftone film 56, and then a resist film is formed by baking. According to a conventional method, an electron beam exposure apparatus (Hitachi Ltd. HL-800M) Then, the phase shift pattern was exposed. Subsequently, post-exposure baking was performed at 130 ° C. for 20 minutes, followed by development with an alkaline aqueous solution containing tetramethylammonium hydroxide as a main component and rinsing with pure water to form a resist pattern.
[0043]
Next, the phase shift film 56 exposed from the opening portion of the resist pattern was exposed from the opening portion of the phase shift pattern formed of a fluorocarbon-based gas by a dry etching apparatus (MEPS-6025 manufactured by ULVAC, Inc.). The transmittance adjusting layer was dry-etched with a halogen-based gas to form a halftone film pattern.
Subsequently, the remaining resist was removed by ashing with oxygen plasma to complete a halftone phase shift reticle 50 provided with a defect-free halftone phase shifter 56 '(FIG. 6 (i)).
[0044]
(Example 4)
FIG. 7 and subsequent FIG. 8 are schematic cross-sectional views showing an example of a phase shifter defect correcting method for a phase shift reticle in the present invention. A light-shielding film pattern 72 having a two-layer structure of a chromium thin film having a thickness of 80 nm and a low reflection chromium thin film having a thickness of 40 nm is provided on a 6-inch square optically polished synthetic quartz glass substrate 71 having a thickness of 0.25 inch. A phase shifter 73 made of silicon dioxide and having a film thickness of 400 nm is provided on the phase shifter 73. The phase shifter 73 is subjected to a visual inspection by a scanning electron microscope (S6280T, manufactured by Hitachi, Ltd.) to detect a foreign object defect 73a and a pinhole defect 73b. It was confirmed that various defects such as surface irregularities were mixed (FIG. 7A).
[0045]
Next, the phase shifter 73 was ground by flattening with a CMP apparatus SPP600S manufactured by Okamoto Machine Tool Manufacturing Co., Ltd. to obtain a flat phase shifter 73 ′ having a thickness of about 300 nm (FIG. 7B). In the flattening step, the level difference of the film disappeared due to the flattening of the surface, and foreign matter in the film was discharged to the outside, so that only the pinhole defect 74 could be confirmed in the flattened phase shifter 73 ′.
[0046]
Next, on the entire surface of the flattened phase shifter 73 ′, a commercially available coating glass (spin-on glass; SOG), Acuglass 211S manufactured by Allied Signal Co., is applied by a spin coating method, and 1 at 300 degrees in a nitrogen atmosphere. The SOG film having a film thickness of about 400 nm after baking was obtained, and this SOG film was used as the second phase shift film 75 (FIG. 7C).
[0047]
Next, a phase shift comprising a planarized second phase shift film 75 ′ having a thickness of about 400 nm and a planarized phase shifter 73 ′ by grinding by planarization polishing using a CMP apparatus SPP600S manufactured by Okamoto Machine Tool Co., Ltd. A film 76 was obtained (FIG. 7D).
The pinhole defect of the planarized phase shifter 73 ′ is buried by forming the second phase shift film, and the surface of the second phase shift film is flattened to eliminate the step of the film, so that the foreign matter in the film is exposed to the outside. Since it was discharged, the defect of the obtained phase shift film 76 could not be confirmed.
[0048]
Next, a positive type i-line resist (THMR-iP3500 manufactured by Tokyo Ohka Kogyo Co., Ltd.) is spin-coated on the phase shift film, a resist film 77 is formed by baking, and a laser exposure apparatus (E-TEC Co., Ltd.) is then formed in accordance with a conventional method. A phase shift pattern exposure 78 was performed by using ALTA-3000 (FIG. 8E).
Subsequently, development was performed with an alkaline aqueous solution containing tetramethylammonium hydroxide as a main component, followed by rinsing with pure water to form a resist pattern 77 ′ for phase shifter (FIG. 8F).
[0049]
Next, the phase shift film 76 exposed from the opening of the phase shifter resist pattern 77 ′ is dry-etched with a carbon fluoride gas by a dry etching apparatus (MEPS-6025 manufactured by ULVAC, Inc.), and the phase is changed. A shifter 76 'was formed (FIG. 8 (g)).
Subsequently, the remaining resist was removed by ashing with oxygen plasma to complete a phase shift reticle 70 provided with a defect-free phase shifter 76 '(FIG. 8 (h)).
[0050]
(Example 5)
In the fourth embodiment, the phase shifter defect correcting method of the Levenson type phase shift reticle is taken up. However, the phase shifter defect is corrected by the same method as that of the fourth embodiment in the halftone phase shift reticle, and the phase shifter has no defect. A phase shift reticle was completed.
[0051]
【The invention's effect】
As described above, in the method of manufacturing a phase shift reticle of the present invention, the phase shift film is formed by a combination of two or more phase shift film forming methods and two or more phase shift film surface polishing steps. In addition, by patterning the phase shift film, it is possible to eliminate phase shifter defects as much as possible without affecting the lower layer of the shifter, and to eliminate the phase shifter defects as much as possible. A shift reticle can be manufactured.
[0052]
Furthermore, in the phase shifter defect correcting method of the phase shift reticle of the present invention, it comprises a combination of two or more phase shift film surface polishing steps and one or more phase shift film formation steps for a defective phase shifter, By patterning the phase shift film, the phase shift reticle can be corrected. By eliminating defects in the phase shift layer without affecting the lower layer of the phase shifter, various phase shifter defects such as foreign matter defects, pinhole defects, crack defects, and surface irregularities due to lower steps can be easily removed. It can be eliminated in the process.
[Brief description of the drawings]
1 is a schematic cross-sectional view showing a method for producing a Levenson type phase shift reticle of the present invention of Example 1. FIG.
FIG. 2 is a schematic cross-sectional view showing the method of manufacturing the phase shift reticle of the present invention following FIG.
3 is a schematic cross-sectional view showing a method for manufacturing the halftone phase shift reticle of the present invention of Example 2. FIG.
4 is a schematic cross-sectional view showing the method of manufacturing the phase shift reticle of the present invention following FIG. 3. FIG.
5 is a schematic cross-sectional view showing another example of the method for manufacturing the halftone phase shift reticle of the present invention in Example 3. FIG.
6 is a schematic cross-sectional view showing the manufacturing method of the phase shift reticle of the present invention following FIG. 5. FIG.
FIG. 7 is a schematic cross-sectional view showing a phase shifter defect correcting method for a phase shift reticle of the present invention.
FIG. 8 is a schematic cross-sectional view showing the phase shifter defect correcting method for the phase shift reticle of the present invention following FIG. 7;
FIG. 9 is a schematic cross-sectional view showing a conventional method of manufacturing a phase shift reticle.
FIG. 10 is a schematic cross-sectional view showing a conventional phase shifter defect correcting method for a phase shift reticle.
[Explanation of symbols]
10, 30, 50, 70 Phase shift reticle
11, 31, 51, 71 Transparent substrate
12, 72 Light-shielding film pattern
13, 33, 53 First phase shift film
13 ', 33', 53 'flattened first phase shift film
13a, 33a, 53a, 73a Foreign object defect
13b, 33b, 53b, 73b Pinhole defect
13c Step defect
14, 34, 54, 74 Pinhole defects
15, 35, 55, 75 Second phase shift film
15 ', 35', 55 ', 75' surface-polished second phase shift film
16, 36, 56, 76 Phase shift film
16 ', 36', 56 ', 76' phase shifter
17, 37, 77 Resist film
17 ', 37', 77 'resist pattern
18, 38, 78 pattern exposure
52 Permeability adjusting membrane
57 Third phase shift film
57 'surface-polished third phase shift film
58 Fourth phase shift film
58 'surface-polished fourth phase shift film
73 Phase Shifter
73 'Flattened phase shifter
91, 101 Transparent substrate
92, 102 Light shielding film pattern
93 Phase shift film
94 Foreign object defect
95, 105 Pinhole defect
96 Phase shifter
97 Step defect
103 Phase shifter
104 Convex defect
106 Focused ion beam optical system assist gas introduction
107 Carbon deposition of focused ion beam optical system
108 Molded film

Claims (5)

In the method of manufacturing a phase shift reticle, a step of forming a first phase shift film on a substrate, a step of polishing the surface of the phase shift film to flatten the film and discharge foreign matter in the film, and the polished phase Forming a second phase shift film having optical properties similar to those of the first phase shift film on the shift film, and filling a pinhole defect in the first phase shift film; and the second phase A step of polishing the surface of the shift film, and a step of patterning the phase shift film obtained by adding the first phase shift film and the second phase shift film to form a phase shifter,
A phase shift reticle manufacturing method, wherein a phase shift of exposure light when using a phase shift reticle of a phase shift film obtained by adding the first phase shift film and the second phase shift film is 180 degrees. In the method of manufacturing a phase shift reticle, a step of forming a first phase shift film on a substrate, a step of polishing the surface of the phase shift film to flatten the film and discharge foreign matter in the film, and the polished phase Forming a second phase shift film having optical properties similar to those of the first phase shift film on the shift film, and filling a pinhole defect in the first phase shift film; and the second phase A step of polishing the surface of the shift film, and a step of polishing the surface by additionally forming a phase shift film having the same optical properties as the first phase shift film on the surface-polished second phase shift film A step of forming a laminated phase shift film, and a step of patterning the laminated phase shift film to form a phase shifter,
A phase shift reticle manufacturing method, wherein a phase difference of exposure light when the phase shift reticle of the laminated phase shift film is used is 180 degrees. 2. The method of manufacturing a phase shift reticle according to claim 1, wherein the phase difference of the exposure light when using the phase shift reticle is 180 degrees or 180 degrees in the step of forming the first phase shift film on the substrate and polishing the surface. A method of manufacturing a phase shift reticle, characterized in that the phase shift film is ground to a thickness that can be further reduced. In the method of correcting phase shifter defects of a phase shift reticle, a step of polishing the surface of the phase shifter after cleaning and drying the phase shift reticle, and a phase shift film having the same optical properties as the phase shifter are formed on the entire surface. And surface polishing and flattening to fill the pinhole defect, and patterning the phase shift film to form a phase shifter,
The phase shifter has a phase difference of 180 degrees in exposure light when the phase shift reticle is used. 5. The phase shifter defect correcting method for a phase shift reticle according to claim 4, wherein after the step of planarizing the phase shift film and filling the pinhole defect in the surface polishing step, the optical properties similar to those of the phase shift film are exhibited. A step of additionally forming a phase shift film and polishing the surface; and a step of patterning the phase shift film to form a phase shifter,
The phase shifter has a phase difference of 180 degrees in exposure light when the phase shift reticle is used.

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