JP2002088478A - Film deposition method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a film deposition method in which a defect repair process for structures by which both of projecting defects and recessed defects can flatly be repaired in accordance with the surface of a base board can be utilized. SOLUTION: This film deposition method includes a process in which, by FIB assist deposition in which a material having an Si-O-Si bond and an Si-H bond is fed to the surface of a structure, and further, a desired part in the surface fed with the above material is irradiated with a focused ion beam, a silicon oxide film is deposited.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a film forming method which can be used in a process for correcting a convex defect or a concave defect of a structure, and more particularly to a method suitable for use in a defect correcting process of a phase shift mask. It relates to a membrane method.

[0002]

2. Description of the Related Art In recent years, as a mask for transferring an LSI pattern onto a wafer, a phase shift mask which improves resolution by using a phase shift effect has been used. In such a phase shift mask, if a defect exists in the shifter, good pattern transfer cannot be performed. Therefore, when a defect occurs, it is necessary to surely correct the defect.

[0003] When a convex defect is present in a shifter of a phase shift mask, a method has been proposed in which the convex defect is etched by irradiating the defect with a focused ion beam (hereinafter abbreviated as FIB) to correct the defect. ing. However, since the phase shifter and the mask substrate are often made of the same material, it is difficult to detect the end point of the etching of the convex defect by this method. Further, it is extremely difficult to etch only the convex defect, and even if only the convex defect can be etched, the shape of the shifter after etching depends on the shape of the convex defect.

In order to solve this problem, the convex defect is covered with a deposition film so that the upper surface of the film becomes flat, and the convex defect and the deposition film include the convex defect under the condition that the etching rate is the same. A method is considered in which the deposited film is etched to remove the convex defects together with the deposited film.

[0005]

SUMMARY OF THE INVENTION However, FIB
In the case of assist deposition using the method, it is difficult to form the upper surface of the film flat when covering the convex defect depending on the type of the deposited film. As the thickness of the deposited film is increased to a certain extent, the step of the deposited film at the portion covering the edge of the convex defect becomes smaller, but even if a thicker film is formed, the step of the deposited film hardly becomes zero. When a film having a step is etched, the shape after the etching depends on the shape of the step, and it becomes difficult to remove the convex defect and make the film flat.

[0006] On the other hand, it is extremely difficult to correct a concave defect by making the surface of the buried portion flush with the surface of another shifter.

As described above, conventionally, it is conceivable to use the FIB to correct the defect of the phase shift mask. However, since it is difficult to form a deposited film on the defect flatly, the defect is formed on the substrate surface. It is difficult to correct the flatness together.

The present invention has been made in consideration of the above circumstances, and an object of the present invention is to provide a structure capable of repairing any of a convex defect and a concave defect to be flat according to the substrate surface. An object of the present invention is to provide a film forming method that can be used in a body defect repair process.

[0009]

In order to solve the above problems, the present invention employs the following configuration.

That is, the first invention of the present invention is directed to Si—O—
Forming a silicon oxide film by FIB-assisted deposition of supplying a material having a Si bond and a Si—H bond to the surface of the structure and irradiating a focused ion beam to a desired portion of the surface supplied with the material; And a film formation method characterized by including:

[0011] The second invention of the present invention is directed to Si-O-
A FIB assist device that supplies a material having a Si bond and a Si—H bond and a gas containing an oxygen element-containing material to a surface of a structure and irradiates a desired portion of the surface supplied with the material with a focused ion beam. A film forming method characterized by including a step of forming a silicon oxide film depending on a position.

[0012] In the film forming method according to the first invention, the energy of the focused ion beam, the current density of the focused ion beam, and the FIB assist deposition before the step of forming the silicon oxide film. The method may further include determining at least one set value of the gas pressure. In this case, the FIB assist deposition is
At least one of the energy of the focused ion beam, the current density of the focused ion beam, and the gas pressure at the time of the FIB assist deposition may be adjusted to the set value.

Further, in the film forming method according to the second invention, before the step of forming the silicon oxide film, the energy of the focused ion beam, the current density of the focused ion beam, and the And determining at least one set value of the gas pressure and the gas partial pressure during the FIB assist deposition. In this case, the FIB assist deposition is performed by at least the energy of the focused ion beam, the current density of the focused ion beam, the gas pressure during the FIB assist deposition, and the gas partial pressure during the FIB assist deposition. One may be performed according to the set value.

Preferred embodiments of the present invention include, for example, the following. (1) The material having the Si—O—Si bond and the Si—H bond has a cyclic structure. (2) The material having a Si—O—Si bond and a Si—H bond is 1,3,5,7-tetramethylcyclotetrasiloxane. (3) A Ga beam or a Si beam is used as a focused ion beam. (4) The oxygen-containing material is a material selected from the group consisting of O ₂ , O ₃ , and N ₂ O.

The film forming method of the present invention can be used, for example, in first and second defect repair processes described below. That is, the first defect repair process is a method of repairing a structural defect that corrects a convex defect generated in a structure having a substrate and a desired pattern provided on the substrate,
Forming a first thin film made of a material different from a material constituting a base of the convex defect so as to be around the convex defect or close to the convex defect; Forming a second thin film on the thin film and flattening the upper surface thereof, and charging the convex defect and portions of the first and second thin films located above and around the convex defect with a charged particle beam And a step of removing a portion of the first and second thin films remaining in the removing step.

A second defect repairing process is a method of repairing a concave defect generated in a structure having a substrate and a desired pattern provided on the substrate, the method comprising: A step of embedding an embedding material in the concave defect and forming a protruding portion protruding from the surface where the concave defect has occurred, and forming a region including the protruding portion from a material different from a material constituting the surface region where the concave defect has occurred. Covering with a flattening film, and flattening the upper surface thereof; simultaneously removing the protrusions and portions of the flattening film located above and around the protrusions using a charged particle beam; and Removing a portion of the oxide film remaining in the removing step.

Here, the flattening film in the second defect repair process may have a stacked structure of the first and second thin films as in the first defect repair process.

Embodiments of these defect repair processes include the following.

(1) The first and second thin films are made of a material containing carbon that has been assisted by FIB. This assist deposition should be performed using a hydrocarbon gas. The hydrocarbon gas is methyl methacrylate gas, 2,4,4-trimethyl-1-pentene gas, or isoprene gas.

(2) The first and second thin films are made of a material containing tungsten assisted by FIB. This assist deposition should be performed using W (CO) ₆ or WF ₆ .

(3) The flattening film is made of a photosensitive resin or a resin which is crosslinked or decomposed by charged particles.

(4) In the simultaneous removal step, the convex defect or the protrusion and the first and second thin films are removed at the same processing rate by controlling the processing conditions.

(5) In the simultaneous removal step, the convex defects or protrusions and the first and second thin films are removed by FIB sputtering and / or assisted etching of charged particles. This assist etching is performed using a gas containing an XeF ₂ gas and / or an oxygen element. The gas containing an oxygen element is O _2, ozone, or N ₂ O.

(6) In the simultaneous removal step, the processing end points of the convex defect or the projection and the first and second thin films are determined by measuring the secondary particles emitted from both.

(7) The first and second thin films remaining in the simultaneous removal step are subjected to thermal etching using laser light, O ₃ or O ₂
Reactive etching using laser light in atmosphere, O ₂ plasma asher, chemical dry in which at least one of CF ₄ , H ₂ , H ₂ O, N ₂ , N ₂ O and NO is added to O ₂ gas Etching (hereinafter abbreviated as CDE),
C using hydrogen gas or gas containing hydrogen atom in molecule
Removal by DE or RIE or FIB assisted etching using O ₃ or O ₂ .

(8) The photosensitive resin remaining in the simultaneous removal step or the resin which is crosslinked or decomposed by the charged particles is removed using a stripper.

(9) After the removing step using the charged particle beam, the damaged layer on the substrate surface is removed.

(10) After the removing step using the charged particle beam,
Removing the damaged layer on the surface of the substrate by assist etching using a gas containing at least XeF ₂ or thermal etching using a laser beam;

(11) The embedding material is the same material as the substrate.

(12) The embedding material must have the same optical characteristics, particularly transmittance and refractive index, as the substrate material.

(13) The embedding of the concave defect is performed in two or more steps.

(14) The embedding of the concave defect is performed by a charged particle beam (FI
B or electron beam).

(15) The gas having a Si—O bond and / or a Si—H bond in assist deposition for embedding a concave defect is 1,3,5,7-tetramethylcyclotetrasiloxane. The gas containing an oxygen element is oxygen, ozone, or N ₂ O. FIB is Ga
Beam or Si beam.

(16) A gas having a Si—N bond and / or a Si—H bond and a gas containing nitrogen as a main component are used for assist deposition for embedding a concave defect. The gas containing the nitrogen element is nitrogen or ammonia.

Among the above defect repair processes, the convex defect repair process is characterized in that a flat film is formed on the convex defect, and the FIB processing conditions for simultaneously forming the deposited film and the convex defect at the same etching rate. To remove by etching,
Another object of the present invention is to determine the end point of the processing by detecting the inflection point of the ratio of the secondary ions emitted from the deposited film and the convex defect.

Here, if the film formed on the convex defect is not flat, there is a problem that the surface shape after both etching simultaneously depends on the shape of the deposited film, and the convex defect cannot be corrected flat. Therefore, in the present invention, when a film is formed on a convex defect, first, a desired interval is provided from the convex defect to make the upper surface of the film covering the convex defect easier.
Is formed, and then a second thin film is formed so as to cover the convex defect and the first thin film.

The feature of the concave defect repairing process among the above defect repairing processes is that the embedding material is slightly protruded from the defect in accordance with the shape of the concave defect, is deposited, and then the above-mentioned convex defect repairing process is performed. The modification process can be applied.

As described above, if the above-described defect repair process is applied, any of a convex defect and a concave defect can be repaired flat in accordance with the substrate surface, which is extremely useful for repairing a defect such as a phase shift mask. It is valid.

The film forming method of the present invention is suitable for forming a first thin film, a second thin film, and the like in the above-described defect repair process. The film forming method of the present invention is suitable for use in the above-described defect repair process, but can also be used for other defect repair processes. Further, the film forming method of the present invention can be used for applications other than defect repair. In particular, the film forming method of the present invention is useful for forming a fine thin film pattern.

[0040]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The details of the present invention will be described below with reference to the illustrated embodiments.

(Example 1) In a first example, a method for correcting a convex defect of silicon oxide generated on a mask substrate of a phase shift mask will be described.

The feature of the convex defect repairing process is that a flat film is formed on the convex defect by using the FIB apparatus, and the deposited film and the convex defect are simultaneously removed by etching under the FIB processing condition of the same etching rate. And an attempt to determine the end point of the processing by detecting the inflection point of the ratio of the secondary ions emitted from the deposited film and the convex defect at that time. Therefore, if the film formed on the convex defect is not flat, the surface shape after etching both of them at the same time depends on the shape of the deposited film, and the problem that the convex defect cannot be corrected flat occurs. In the process, formation of a flattening film is most important.

FIG. 1 shows a schematic configuration of an FIB apparatus used in the method of the present embodiment. This apparatus has a well-known configuration, 1 is an ion source, 2 is a magnifying lens, 3 is a mass separation mechanism, 4 is a deflector, 5 is an objective lens, 6 is a charge nutrizer, 7
Is a secondary ion detector, 8 is a sample, 9 is a sample stage, 1
1 denotes a gas cylinder, 12 denotes a capacitance type pressure gauge (Baratron), and 13 denotes a nozzle.

FIGS. 2 and 3 show a process flow for correcting the convex defect 102 of the phase shifter formed on the quartz substrate 101. FIGS. 2A and 3A are sectional views. 2 (B) and 3 (B) show plan views.

As shown in FIGS. 2 (A1) and 2 (B1), the phase shift mask is a phase shift mask utilizing a shifter edge in which a phase shifter pattern 103 made of silicon oxide is formed on a quartz substrate 101, for example. . Assuming that the wavelength of the exposure light source is λ and the refractive index is n, the thickness t of the phase shifter for inverting the phase is t = λ / ｛2 (n−
1) It is represented by an odd multiple of｝. Here, KrF is used as a light source (λ = 248 nm), and the phase shifter is a silicon oxide film (n
= 1.508), so that t = 244 nm.

First, the defect is corrected using the FIB apparatus shown in FIG. 1 based on information such as the size, shape (convex or concave), and position of the defect obtained by using a general defect inspection apparatus. Recognize the defects that should be. Thus, it is assumed that the convex defect 102 has been recognized.

After the defect has been confirmed, FIG. 2 (A 2), FIG.
As shown in (B2), the first thin film 104 is cut into a donut shape with a slight space around the convex defect 102.
Deposit to the same height as 2. The deposited film 104 is made of, for example, GaFI accelerated to 20 keV at room temperature (25 ° C.).
It is formed by assist deposition in which pyrene gas is decomposed by B to deposit carbon (C). Here, since the first deposited film 104 needs to be finally removed, the substrate 10
It is essential that the selectivity with 1 is sufficiently large.

Next, as shown in FIGS. 2A and 2B, a second deposited film 105 is formed in a region covering the convex defect 102 and the first deposited film 104. The formation of the second deposited film 105 is performed by the assist deposition similarly to the formation of the first deposited film 104.

Here, the convex defect 102 and the first deposited film 1
04 and the second deposited film 105 having a thickness of 1.0 μm.
There is a relationship as shown in FIG. 4 between the depth y of the surface dent generated when forming with m. That is, y decreases as x decreases. This is because, in the assist deposition using an ion beam and a gas, deposition proceeds by ions and secondary electrons scattered multiplely inside the narrow groove. This is because film formation speed becomes faster, y becomes smaller, and a flat film can be obtained. In the above-described two-stage carbon film deposition method, when the convex defect is small or when the pattern is close to the defect to be corrected, only the one-stage carbon film may be formed.

Next, as shown in FIGS. 3A4 and 3B4, the flat film (10
4, 105) and the convex defect 102 are simultaneously etched back (flattened and the flattened film and the object to be etched are simultaneously etched) at the same rate. For example, 2
Carbon film 1 formed of 0 keV GaFIB and pyrene gas
Convex defect 102 composed of silicon oxide films 04 and 105 and silicon oxide film
When performing sputter etching with GaFIB at room temperature, the etching rate ratio of C / SiO ₂ changes depending on the acceleration voltage of GaFIB as shown in FIG.
At V, the etch rate ratio of C / SiO ₂ is about 1. Therefore, under this condition, a region slightly larger than the convex defect 102 is raster-scanned by using the beam 106 narrowed down finely, and carbon and SiO ₂ can be simultaneously removed at the same etching rate.

When the ratio of the secondary ions of carbon and Si generated during this processing is measured by using the mass spectrometer 107, the moment when the carbon around the convex defect 102 disappears in the beam scanning area is determined. Since the secondary ion ratio of C / Si greatly changes, it can be determined that the convex defect 102 has been cut to the same height as the surface of the substrate 101. Also, the end point can be determined using the secondary ion ratio of C / O instead of the secondary ion ratio of C / Si. A method of determining the end point of the process using such measurement of secondary ions is disclosed in, for example, Japanese Patent Application Laid-Open No. 58-106750. In addition, carbon and SiO ₂ can be detected by detecting secondary electrons.
Can be determined.

However, in the sputtering using GaFIB, a damage layer 108 having a depth of about 15 nm remains on the surface of the sputtered substrate 101, and the transmittance of light used for exposure is reduced. For this reason, the convex defect 102
After the removal is completed, the damaged layer 108 is assist-etched using, for example, XeF ₂ gas and GaFIB at room temperature as shown in FIGS. 3 (A5) and 3 (B5). Since a damaged layer cannot be formed by the assist etching using this gas, the damaged layer 108 can be removed. When the sample temperature is lower than room temperature, gas adsorption proceeds and etching can be more effectively performed. Although this processing results in a recess of about 15 nm, such a recess does not transfer to the wafer and does not affect the surrounding pattern. It should be noted that assist etching can be similarly performed by using an electron beam instead of GaFIB.

Finally, as shown in FIG. 3 (A 6) and FIG. 3 (B 6), carbon remaining around when removing the convex defect is removed by O _2.
Removed by plasma asher. For example, when ashing is performed by flowing O ₂ gas so that the inside of the chamber becomes 0.9 Torr and applying a high frequency power of 500 W,
Carbon can be removed without damage. Removal of carbon, O ₂
Not plasma asher only, it is possible to perform even CDE using O ₂ gas or CF ₄ O ₂ gas was added. Further, it is effective to keep the substrate temperature at 150 to 400 ° C. Further, the removal can be performed by laser beam irradiation or FIB irradiation in an O ₂ or O ₃ atmosphere.

It is more efficient to remove the remaining carbon collectively after all the defects have been corrected. Also, the order of the last two steps, ie, the carbon removing step and the damage removing step, can be changed.

Here, the steps formed on the substrate surface when the convex defect is repaired by using the above repair process will be described. The step formed by the correction is obtained by adding the convex or concave step De formed by the difference in the etching rate between the flattening film and the defect to the sum of the dent amount y of the flattening film and the dent amount Dy that can remove the damaged layer. Amount.
Therefore, the step formed in this manner must be naturally suppressed to a level not causing a line width variation allowed for the transfer pattern.

Taking the Levenson type phase shift mask as an example, if an allowable value is 10% of the minimum resolution, the wavelength 2
48 nm, minimum dimension 0.25 μm, stepper NA = 0.
45, coherence factor indicating coherence of exposure wavelength: about 40 nm, wavelength 365 nm, minimum dimension 0.35 μm, NA of stepper = 0.46, coherence factor indicating coherence of exposure wavelength when σ = 0.3 It becomes about 80 nm when σ = 0.3. That is, if the amount of the step is less than the above, there is no problem in the transfer performance of the phase shift mask. In other words, the processing conditions in each step can be relaxed until (y + Dy + De) becomes the above-mentioned step. That is, if the wavelength KrF is y = 10 nm and Dy = 15 nm, the etching rate ratio (0.94 to 1.06) can be relaxed until De reaches a maximum of 15 nm.

As described above, if the convex defect is corrected according to the correction process flow of the present embodiment, the following effects can be obtained.

(1) Flattening film (first deposited film 104, second deposited film 105) over a wider range than convex defect 102
Therefore, it is possible to minimize the occurrence of damage around the defect region caused by the irradiation of the Ga beam at the time of defect removal.

(2) Flattening films (104, 10) of different materials
5) and the convex defect 102 are simultaneously processed to form a flattening film (C).
And the secondary ions emitted from the defects (SiO ₂ ) or their secondary ion ratios or secondary electrons are measured, so that the end point of the processing can be easily detected.

(3) By flattening the convex defect 102 having an irregular thickness using the flattening films (104, 105), a flat shape after repair can be easily obtained.

(4) Damage layer 108 remaining on substrate 101
Can be easily removed by assisted etching using XeF ₂ and GaFIB or an electron beam.

(5) The carbon film (10
4, 105) can also be easily removed by the O ₂ plasma asher without causing any other damage.

(6) Most repairs can be made by using a GaFIB device and changing only the type of gas introduced into the device, so that extremely efficient defect repair can be performed.

Although the process of repairing a convex defect has been described above, the repair process is not limited to the above example.

In the above example, a carbon film formed using pyrene gas as a raw material was described as a flattening film covering a convex defect. However, a carbon film formed using another hydrocarbon gas as a raw material, such as W (CO) _6, is used. Alternatively, a tungsten film formed using such a tungsten film may be used. The coverage of the tungsten film was almost the same as that of the carbon film. When the above-described two-step deposition was performed at room temperature, a flat film with a small dent on the surface could be obtained similarly to the carbon film. Further, in the simultaneous processing of the defect (SiO ₂ ) and the tungsten film, the etching rate ratio is about 1
Is in the acceleration voltage range of a general FIB device.

As the flattening film covering the convex defect,
Not only a film formed by FIB but also a film made of a photosensitive resin or a resin crosslinked or decomposed by charged particles may be used. In this case, after applying these resins onto a reticle by spin coating, a laser beam or a slit is used to squeeze only an area including a desired defect using a microscope or using coordinates obtained in an inspection process. Irradiated with light, FIB, or an electron beam. By developing this, a flattening film is formed. The formation of the first thin film and the second thin film is performed by repeating the above steps, and the film thickness is adjusted by adjusting the exposure amount (irradiation light amount) or the resist concentration when exposing the resist. When the convex defect is small or when the pattern is close to the defect to be corrected, it is only necessary to form the flattening film once.
Thereafter, the same processing as the carbon film formed by using the FIB using pyrene gas as a raw material can be performed. Also,
When a photosensitive resin or a resin crosslinked or decomposed by charged particles is used, it can be removed using a stripping solution such as a mixed solution of sulfuric acid and hydrogen peroxide.

Although the simultaneous etching of carbon and SiO ₂ is performed by GaFIB in the above example, FIB using gas or electron beam assisted etching can also be used. In this case, the etching rate of the deposited film and the shifter can be controlled by selecting and combining the gases.
Furthermore, if a mixed gas of XeF _{2 is used} as a gas, no damage layer remains on the substrate surface during defect removal, and the damage layer removal step in the above-described process flow can be reduced, so that it is not necessary to perform extra excavation. it can. in this case,
There is a point in the general acceleration voltage range where the etching rate of carbon and SiO ₂ is about 1, and the absolute etching rate is higher than in the case of sputter etching, so that the throughput can be improved.

In the case of sputtering using GaFIB, the sputtering yield of, for example, a quartz substrate becomes saturated with time (FIG. 6). This is because in sputtering, the sputtered material re-adheres around the processing area, and the sputtering yield saturates over time. On the other hand, in the assist etching using the XeF ₂ gas and GaFIB or the electron beam, the etching yield of the quartz substrate is always constant because there is no re-adhesion effect (FIG. 7), and the controllability of the processing is extremely good. can get.

Although the removal of carbon remaining after the removal of the defect has been performed by the O ₂ asher in the above description, for example, a laser may be used. This method utilizes the evaporation of carbon due to absorption of laser light.The laser light is squeezed finely using a slit, and when it irradiates residual carbon, the laser energy is absorbed by the carbon and becomes heat, which causes the sublimation and scattering of the carbon. I do.
Moreover, at this time, laser energy is absorbed in the damaged layer, and the damaged layer is removed in the same manner as carbon. The two steps of removing the residual carbon and removing the damaged layer are reduced to one step, and the repair process is more efficiently performed.

Another method is to react C with O ₂ or O ₃ by irradiating a laser beam in an O ₂ or O ₃ atmosphere to remove CO and CO ₂ . In this case, since the chemical reaction is used, the power of the laser beam can be reduced, and even if the laser beam is applied to the light shield near the defect, the light shield does not evaporate and only the carbon is removed. There are conditions that can be achieved. Therefore, there is an advantage that the tolerance of the beam diameter of the laser beam and the tolerance of the alignment are increased, and the process margin is increased. In addition, since heating can be locally performed by using a laser, pattern distortion due to heat can be suppressed. Further, the same effect can be expected by using FIB instead of laser light in an O ₂ or O ₃ atmosphere. In this case, in order to obtain a selectivity between the substrate and carbon, light ions are used or the acceleration energy is set to 10 or more.
It is necessary to use an FIB having a keV or less.

The carbon deposition, the simultaneous etching of carbon and SiO ₂ , and the removal of the damaged layer are all performed by GaFIB, but are not limited to these ions. For example, it is apparent that the processes in the above steps may be performed using other ions such as Au and Si.

(Example 2) In a second example, a method of correcting a shifter concave defect will be described in detail with reference to FIG. First, a defect to be corrected is recognized using an FIB device based on information such as the size, shape (whether convex or concave), and position of a defect obtained using a general defect inspection device. As shown in FIG. 8A, after a concave defect 202 is confirmed in the phase shifter 201, a Si-
A gas having an O bond and / or a Si—H bond or a mixed gas containing the same, for example, a mixed gas 204 of 1,3,5,7-tetramethylcyclotetrasiloxane and oxygen (mixing ratio = 1: 3) is sprayed. Meanwhile, a region slightly larger than the concave defect 202 is irradiated with 50 keV Si ²⁺ FIB 205. As a result, as shown in FIG.
SiO ₂ film (embedding material) slightly protruding from one surface 2
06 is deposited. The diameter of the nozzle used here is 0.2 mm,
The pressure in the capacitance type pressure gauge shown in FIG. 1 was 4 Torr. At this time, the total gas flow rate at the nozzle outlet is 0.05
sccm.

The 0.4 μm thick S thus deposited
The light transmittance of the iO ₂ film for light having a wavelength of 436 nm is 100.
%, And the light transmittance of a film (SiO _x ) formed using a conventional mixed gas of tetramethoxysilane and oxygen is 40%.
Optical characteristics are better than Further, the light transmittance of the SiO ₂ film formed by the method of the present example with respect to light having a wavelength of 248 nm (light used in the Levenson-type phase shift mask method) is 90.6%, which is the light transmittance required for correcting a concave defect. Rate (80.6%) or more.

If it is necessary to improve the light transmittance of the deposited film, the following post-processing may be performed. After film deposition, UV light having a power density of 200 mW / cm ^{2 on} the surface of the deposited film is irradiated for one hour. Moreover, such a deposited film having a similar light transmittance even if the film formation while irradiating UV light instead of UV light treatment is obtained, 350 ° C. The film formed on the other in an O ₂ atmosphere, The same effect can be obtained by performing the annealing treatment for one hour.

Here, the above two types of gases may be sprayed from separate nozzles, respectively, and O ₃ ,
A gas containing oxygen as a main component such as N ₂ O may be used. The gas mixture ratio is not limited to 1: 7,
The mixing ratio may be such that the deposit is transparent and the concave defect is well-shaped according to the ion species and energy of B. For example, T
When EOS (tetraethoxysilane) is used, "spot" is formed inside the deposit at room temperature, but when the mask temperature is lowered to about -70 degrees, "spot" is not formed and the concave defect can be filled. . FIB energy and ionic species are not only 50 keV Si ²⁺ FIB but also 25 keV.
Other energies and ion species such as Ga ⁺ FIB of V can be selected. Further, an electron beam may be used instead of the FIB.

However, when the charge nutrizer is near the gas nozzle and radiation heat from the electron emission filament in the nutrizer affects the gas, black contamination made of carbon adheres to the mask substrate. Therefore, it is desirable to dispose the charge nut riser away from the gas nozzle.

Next, as shown in FIG.
₂ Around the protrusion of the film 206,
Is formed in a donut shape up to the same height as the SiO ₂ film 206. This deposited film 207 is, for example, 20 ke
It is formed by assist deposition in which pyrene gas is decomposed by GaFIB accelerated to V to deposit carbon (C).

Next, as shown in FIG.
_{A second} deposited film 208 is formed in a region covering the protrusion of the _second film 206 and the first deposited film 207. SiO _{2 at} this time
The distance between the distance x between the projecting portion of the film and the first deposited film 207 and the depth y of the surface dent generated when the second deposited film 208 is formed with a thickness of 1.0 μm is shown in FIG. There is a relationship as shown in FIG. That is, y decreases as x decreases.
This is because, in the assist deposition using the ion beam and the gas, the deposition proceeds by the ions and secondary electrons scattered multiplely inside the narrow groove, so that the protrusion of the SiO ₂ film 206 or the first deposition film 207 is formed. This is because the film formation speed becomes higher inside the groove, y becomes smaller, and a flat film is obtained.

Then, as shown in FIG. 8E, the flat films (207, 208) thus formed and Si
The protrusion of the O ₂ film 206 is simultaneously etched at the same rate. For example, a carbon film (207, 208) formed of the above-described 20 keV GaFIB and pyrene gas and SiO
_When the protrusion of the film 206 is sputter-etched with GaFIB, as shown in FIG. 5, the etching rate ratio of C / SiO ₂ changes depending on the acceleration voltage of GaFIB. The etching rate ratio of ₂ is about 1. Therefore, the beam 20 narrowed down under this condition is narrowed down.
The area slightly larger than the protruding portion can be raster-scanned by using 9 to simultaneously remove carbon and SiO ₂ at the same etching rate.

When the ratio of the secondary ions of carbon and Si generated during this processing is measured using a mass spectrometer 210, the carbon around the protrusion of the SiO ₂ film 206 in the beam scanning area is reduced. Since the secondary ion ratio of C / Si greatly changes at the moment of disappearance, it can be determined that the protrusion of the SiO ₂ film 206 has been cut to the same height as the surface of the shifter 201.
Further, it is also possible to determine the end point using the secondary ion ratio of C / O instead of the secondary ion ratio of C / Si.

However, the damage layer 211 having a depth of about 15 nm remains on the processed substrate surface by the sputtering process using GaFIB, and the transmittance of light used for exposure is reduced. For this reason, after the removal of the protruding portion of the SiO ₂ film 206 is completed, as shown in FIG. 8F, the damaged layer 211 is assist-etched using, for example, XeF ₂ gas and GaFIB. Since the damage layer 211 does not remain in the assist etching using this gas, the damage layer 2
11 can be removed. In addition, about 1
Although a recess of 5 nm is formed, such a recess does not transfer to the wafer and does not affect the surrounding pattern.

Finally, as shown in FIG.
_{2 The} carbon remaining around when removing the protrusion of the film 206 is replaced with O ₂
Removed by plasma asher. For example, when ashing is performed by flowing O ₂ gas so that the inside of the chamber becomes 0.9 Torr and applying a high frequency power of 500 W,
Carbon can be removed without damage. The removal of carbon can be performed not only with O ₂ plasma asher but also with O ₂ gas or C
CDE using O ₂ gas to which F ₄ is added can also be performed. Further, it is more effective to keep the substrate temperature at 150 to 400 ° C. Further, carbon can be removed by laser light irradiation or FIB irradiation in an O ₂ or O ₃ atmosphere.

It is more efficient to remove the remaining carbon collectively after all the defects have been corrected. Also, the order of the last two steps, the carbon removing step and the damage removing step, can be changed.

As described above, if the concave defect is corrected according to the repair process flow of the present embodiment, the following effects can be obtained.

(1) Since it is not necessary to embed the concave defect 202 in the SiO ₂ film 206 in the shape of the concave, the process becomes extremely simple.

(2) The protruding portion caused by the embedding of the concave defect 202 is covered with the planarizing films (the first deposited film 207 and the second deposited film 208) over a wider range. At the time of removing the portion, it is possible to minimize the occurrence of damage to the periphery of the defective region caused by the Ga beam irradiation.

(3) Flattening films of different materials (207, 20)
8) and the protruding portion of the SiO ₂ film 206 are simultaneously processed, and the secondary ions emitted from the planarizing film (C) and the protruding portion (SiO ₂ ) or the ratio of the secondary ions are measured, thereby processing the protruding portion. Is easy to detect.

(4) Since the protrusions having an irregular thickness are also flattened using the flattening films (207, 208), the repair surface is easily flattened.

(5) The damaged layer 211 remaining on the surface of the corrected concave defect can be easily removed by assist etching using XeF ₂ and GaFIB.

(6) The carbon film (20) used for defect repair
7, 208) can also be easily removed by the O ₂ plasma asher without causing any other damage.

(7) Since most repairs can be made by using a GaFIB device and only changing the type of gas introduced into the device, extremely efficient defect repair becomes possible.

Although the process of repairing a concave defect has been described above, the repair process is not limited to the above example.

In the above example, the carbon film formed by using pyrene gas as a raw material as the flattening film covering the protrusion remaining after the concave defect is buried with SiO ₂ has been described. Film or, for example, W (C
O) A tungsten film formed using ₆ can also be used. The coverage of the tungsten film was almost the same as that of the carbon film. When the above-described two-step deposition was performed, a flat film with small dents on the surface could be obtained similarly to the carbon film. Further, in the simultaneous processing of the protrusion (SiO ₂ ) and the tungsten film, the point where the etching rate ratio becomes about 1 exists in the acceleration voltage range of a general FIB apparatus.

Further, as the flattening film covering the convex defect,
Not only a film formed by FIB but also a film made of a photosensitive resin or a resin crosslinked or decomposed by charged particles may be used. When these films are formed, these resins are applied on a reticle by spin coating, and then a laser beam or a slit is applied only to a region containing a desired defect using a microscope or by using coordinates obtained in an inspection process. Is used to irradiate a focused beam, FIB or electron beam. Then
This is developed to form a flattening film. The formation of the first thin film and the second thin film is performed by repeating the above steps, and the film thickness is adjusted by adjusting the exposure amount (irradiation light amount) or the concentration of the resist when exposing the resist. When the convex defect is small or when the pattern is close to the defect to be corrected, it is only necessary to form the flattening film once. Hereinafter, F
Processing similar to that of a carbon film formed using IB can be performed. When a photosensitive resin or a resin which is crosslinked or decomposed by charged particles is used, it can be removed using a stripping solution such as a mixed solution of sulfuric acid and hydrogen peroxide.

Further, as for the simultaneous etching of carbon and SiO ₂ , the same modification as in the first example is possible. further,
The removal of the flattening film remaining after the removal of the protruding portion can be performed in the same manner as in the first example. Also, carbon deposition, carbon,
An ion source used for simultaneous etching of SiO ₂ and removal of a damaged layer can be modified in the same manner as in the first example.

In the above process, the shape of the concave defect is reduced.
We did not describe it, but we could omit the process depending on the shape.
Can be abbreviated. That is, a concave shape with a large aspect ratio
In the case of a defect, 1,3,5,7-tetramethylcyclotet
SiO using lasiloxane _TwoFig. 9 (A)
become that way. In such a case, irregularities on the surface are defective
Fig. 8
(C) It is not necessary to proceed with the subsequent steps.

In the above example, the recessed defect is buried with a silicon oxide film, but the burying material is not limited to silicon oxide. The embedding material should be selected according to the material of the shifter, and the above-described correction can be similarly performed for silicon nitride, chromium oxide, and the like.

In addition, various modifications can be made without departing from the spirit of the present invention.

(Example 3) In a third example, a method of correcting a concave defect in a shifter-edge portion of a shifter-edge type phase shift mask will be described with reference to FIGS. Here, FIGS. 11A and 12A are cross-sectional views, and FIGS. 11B and 12B are plan views.

First, a defect to be corrected is recognized by using the FIB device based on information such as the size, shape (whether convex or concave), and position of the defect obtained by using a general defect inspection device. As shown in FIGS. 11 (A1) and 11 (B1),
After a concave defect 303 is confirmed at an edge portion of the phase shifter 302 formed on the SiO ₂ substrate 301, a gas having a Si—O bond and / or a gas having a Si—H bond from the nozzle 304 on the concave defect 303. Or a mixed gas containing the same, for example, a mixed gas 305 of 1,3,5,7-tetramethylcyclotetrasiloxane and oxygen (mixing ratio = 1: 1)
7) While spraying, a region slightly larger than the concave defect region is irradiated with 50 keV Si ²⁺ FIB 306. As a result, as shown in FIGS. 11 (A2) and 11 (B2),
A protruding SiO ₂ 307 is deposited in a region wider than the concave defect 303.

Here, the above two types of gases may be sprayed from different nozzles, respectively, and O ₃ ,
A gas containing oxygen as a main component such as N ₂ O may be used. The gas mixture ratio is not only 1: 7, but also the gas type used and FI
The mixing ratio may be such that the deposit becomes transparent in accordance with the ion species and energy of B. FIB energy and ionic species are not only 50 keV Si ²⁺ FIB but also 25 keV.
Other energies and ion species such as Ga ⁺ FIB of V can be selected. Further, an electron beam may be used instead of the FIB.

Next, FIGS. 11 (A3) and 11 (B3)
As shown in FIG.
Of thin films (carbon films) 308, 308 'of the above. At this time, the projected SiO ₂ 307 and the first carbon films 308 and 308 ′
Was set to 0.4 μm or less.

Next, FIGS. 11 (A4) and 11 (B4)
As shown in FIG. 7, the second thin film (carbon film) 309 is
It is formed on the O ₂ 307 and the first carbon films 308 and 308 ′ by the same method as described above. The thickness is about 1 μm.
By doing so, the surface of the second carbon film 309 becomes flat.

Next, FIGS. 12 (A5) and 12 (B5)
As shown in FIG.
And the protrusion 307 are simultaneously etched at the same rate.
For example, when the carbon films 308, 308 ', 309 formed using GaFIB of 20 keV and pyrene gas and the protrusion 307 made of a silicon oxide film are sputter-etched with GaFIB, as shown in FIG. Si
The etching rate ratio of O ₂ changes depending on the acceleration voltage of GaFIB, and the etching rate ratio of C / SiO ₂ becomes about 1 at about 30 kV. Therefore, under this condition, an area slightly larger than the protrusion 307 can be raster-scanned using the beam 310 narrowly narrowed, and carbon and SiO ₂ can be simultaneously removed at the same etching rate.

When the ratio of secondary ions of carbon and Si generated during this processing is measured using a mass spectrometer 311,
At the moment when the carbon around the convex defect disappears in the beam scanning area, the secondary ion ratio of C / Si greatly changes and the protrusion 30
7 can be determined to have been cut to the same height as the surface of the shifter 302. Also, instead of the secondary ion ratio of C / Si,
The end point can be determined using the secondary ion ratio of C / O.

Further, in the case of a concave defect at an edge portion, an extra protrusion generated for correction must be deleted according to the edge. First, an edge position is detected using FIB. Next, the protrusion S protruding from the extension of the edge portion
The scanning area of the beam that can completely remove iO ₂ 313 is determined. One side of the scanning area is aligned with the previously obtained edge position, and the narrowly narrowed beam is raster-scanned and projected.
3, ie, carbon and SiO2 are simultaneously removed at the same etching rate. The end point of the protrusion 313 processing is measured by using a mass spectrometer to measure the ratio of secondary ions of carbon and Si generated during the processing. That is, the projection 313 in the beam scanning area
At the moment when the surrounding carbon disappears, it is determined that the secondary ion ratio of C / Si greatly changes and the protrusion 313 is cut to the same height as the surface of the quartz substrate 301.

However, in the sputtering by GaFIB, the surface of the sputtered substrate has a depth of 15 nm.
Some damage layer 312 remains, lowering the light transmittance used for exposure. Therefore, after the removal of the protrusions 307 and 313 is completed, the damaged layer 312 is assist-etched using, for example, XeF ₂ gas and GaFIB.
Since the damaged layer does not remain in the assist etching using this gas, the damaged layer 312 can be removed as shown in FIGS. 12 (A7) and 12 (B7). This processing results in a recess of about 15 nm, but such a recess does not transfer to the wafer and does not affect the surrounding pattern.

Finally, FIGS. 12 (A8) and 12 (B8)
As shown in FIG.
Waste carbon_TwoRemove by plasma asher.
For example, O_TwoGas to 0.9 Torr inside the chamber
And apply 500 W of high frequency power to
Singing can remove carbon without damage. carbon
Removal of O_TwoO as well as plasma asher_Twogas
Or CF_FourO with added_TwoDo it even with CDE using gas
And it is possible. The removal of residual carbon is
It is more efficient to make a batch after fixing
You. Also, the last step, carbon removal step and damage removal
It is also possible to change the order. In addition, the substrate
It is more effective to keep the temperature at 150 to 400 ° C. Sa
In addition, O _TwoOr O_ThreeIrradiation with laser light in atmosphere or FIB
Irradiation can also remove carbon.

As described above, if the concave defect at the edge portion is corrected according to the correction process flow of the present embodiment, the following effects can be obtained.

(1) Since it is not necessary to bury the concave defect 302 in the shape of the concave with SiO ₂ , the process is extremely simplified.

(2) The protrusion 307 caused by the embedding of the concave defect 302 is covered with the flattening film (the first carbon film 308 and the second C film 309) over a wider range. At the time of removal, it is possible to minimize the occurrence of damage to the periphery of the defect region caused by the Ga beam irradiation.

(3) Flattening films (308, 30) of different materials
9) and the projection 307 are simultaneously processed, and the secondary ions or the secondary ions emitted from the planarization film (C) and the projection (SiO ₂ ) are processed.
By measuring the secondary ion ratio, it is easy to detect the end point of the protrusion processing.

(4) Since the protrusion 307 having a non-uniform thickness is also flattened by using the flattening films (308, 309), the repair surface is easily flattened.

(5) The damaged layer 312 remaining on the surface of the corrected concave defect can be easily removed by assist etching using XeF ₂ and GaFIB.

(6) The carbon film used for defect repair is also O
₂ It can be easily removed by plasma asher without damaging others.

(7) Since most repairs can be made by using a GaFIB device and changing only the type of gas introduced into the device, extremely efficient defect repair becomes possible.

Although the repair process of the concave defect has been described above, the repair process is not limited to the above example.

In the above example, a carbon film formed from pyrene gas as a raw material is described as a planarizing film covering projections remaining after the concave defects are buried with SiO ₂ , but a carbon film formed from another hydrocarbon gas as a raw material is described. Or W (C
O) A tungsten film formed using ₆ may be used. The coverage of the tungsten film was almost the same as that of the carbon film. When the above-described two-step deposition was performed, a flat film with small dents on the surface could be obtained similarly to the carbon film. Furthermore, in the simultaneous processing of the defect (SiO ₂ ) and the tungsten film, the tendency as shown in FIG. 5 is shown with respect to the acceleration voltage, and the point that the etching rate ratio becomes about 1 is a general FIB apparatus. Exists in the accelerating voltage range.

Further, as the flattening film covering the convex defect,
Not only a film formed by FIB but also a film made of a photosensitive resin or a resin crosslinked or decomposed by charged particles may be used. When these films are formed, these resins are applied on a reticle by spin coating, and then a laser beam or a slit is applied only to a region including a desired defect using a microscope or by using coordinates obtained in an inspection process. Is used to irradiate a focused beam, FIB or electron beam. Then
This is developed to form a flattening film. The formation of the first thin film and the second thin film is performed by repeating the above steps, and the film thickness is adjusted by adjusting the exposure amount (irradiation light amount) or the concentration of the resist when exposing the resist. When the convex defect is small or when the pattern is close to the defect to be corrected, it is only necessary to form the flattening film once. Hereinafter, F
Processing similar to that of a carbon film formed using IB can be performed. When a photosensitive resin or a resin which is crosslinked or decomposed by charged particles is used, it can be removed using a stripping solution such as a mixed solution of sulfuric acid and hydrogen peroxide.

As for the simultaneous etching of carbon and SiO ₂ , the same modification as in the first example is possible. further,
The same modification as in the first example can be applied to the removal of carbon remaining after the removal of the protrusion. Also, carbon deposition, carbon, Si
An ion source used for simultaneous etching of O ₂ and removal of the damaged layer can be modified in the same manner as in the first example.

In the above example, the concave defect is buried with a silicon oxide film, but the buried material is not limited to silicon oxide. The embedding material should be selected according to the material of the shifter, and the above-described correction can be similarly performed for silicon nitride, chromium oxide, and the like.

In addition, various modifications can be made without departing from the spirit of the present invention.

(Example 4) In a fourth example, a method for correcting a convex defect at a shifter-edge portion of a shifter edge type phase shift mask will be described with reference to FIG. here,
13A is a sectional view, FIG. 13B is a plan view,
Reference numeral 401 denotes a substrate, 402 denotes a phase shifter, and 403 denotes a convex defect.

First, a defect to be corrected is recognized using an FIB device based on information such as the size, shape (whether convex or concave), and position of the defect obtained using a general defect inspection device. In this case, since the defect protrudes from the edge, this corresponds to a state in which the steps of the repair method shown in FIGS. 11A2 and 11B2 have been completed. Therefore, if the process proceeds according to the following steps, the correction of the convex defect at the edge portion is completed. 11 (A3) and 11 (B3) when they protrude from the edge but are thinner than the shifter film thickness.
FIG. 12 (A5) and FIG. 12 (B5)
Can be omitted.

(Example 5) In a fifth example, a method of correcting an irregular convex defect which is not a rectangular parallelepiped and is made of silicon oxide, which has occurred on a mask substrate of a phase shift mask will be described. The occurrence of such defects is caused by adhesion of dust during etching, remaining resist, pinholes, and the like, and occurs in large numbers.

The feature of the convex defect repairing process is that a flat film is formed on the convex defect by using the FIB apparatus, and the deposited film and the convex defect are simultaneously etched and removed under the FIB processing conditions that have the same etching rate. And an attempt to determine the end point of the processing by detecting the inflection point of the ratio of the secondary ions emitted from the deposited film and the convex defect at that time. Therefore, if the film formed on the convex defect is not flat, the surface shape after both etchings at the same time depends on the shape of the deposited film, and a problem occurs that the convex defect cannot be corrected flat. Therefore, the formation of a flattening film is most important.

FIG. 14 is a process flow for correcting the convex defect 502 of the phase shifter formed on the quartz substrate 501. This phase shift mask is a shifter edge-based phase shift mask in which a silicon oxide phase shift pattern is formed on a quartz substrate 501, for example. The film thickness t of the phase shifter for inverting the phase is t = λ / ｛2 (n−
1) It is represented by an odd multiple of｝. Here, KrF is used as a light source (λ = 248 nm), and the phase shifter is a silicon oxide film (n = 248 nm).
1.508), t = 244 nm.

First, a defect to be corrected is recognized using an FIB apparatus based on information such as the size, shape, film thickness, and position of the defect obtained using a general defect inspection apparatus. Thus, it is assumed that the convex defect 502 is recognized.

Next, a film is formed so as to cover the convex defect flatly. This deposited film is, for example, 20 mm at room temperature (25 ° C.).
It is formed by assist deposition in which pyrene gas is decomposed by GaFIB accelerated to KeV to deposit carbon (C).

When correcting a defect as shown in FIG. 14A, the same method as in Example 1 is used, that is, FIGS.
As shown in FIG. 3B, a first deposited film 503 is formed in a donut shape at a slight interval around the defect 502 to the same height as the defect 502, and then the convex defect 502 and the first deposited film 503 are formed. If only the second deposited film 504 is formed so as to cover it, the result is as shown in FIG. as a result,
The second deposition film 504 needs to be deposited very thickly for planarization, which is not practical.

Therefore, based on the information on the defect shape obtained by the defect inspection apparatus, as shown in FIG. 14B, an appropriate distance is set so as to be the same as the highest portion of the convex defect 502. To form a first deposited film 503. Next, as shown in FIG.
2 and the second deposited film 50 in a region covering the first deposited film 503.
4 is formed.

The distance x between the first deposited films 503 can be determined from the relationship between the distance x and the depth y of the flat recess when the thickness of the second deposited film 504 is kept constant. For example, when the second deposited film 504 is formed with a thickness of 1.0 μm, there is a relationship as shown in FIG. That is, y decreases as x decreases. This is because, in the assist deposition using an ion beam and a gas, the deposition proceeds by ions and secondary electrons scattered multiplely inside the narrow groove, so that the film deposition rate is higher in the groove than on the first deposited film 503. Is faster, y is smaller, and a flat film can be obtained.

In the above description, the convex defect is flattened in two stages. However, when the convex defect has severe irregularities as shown in FIG. 16 (A), FIGS. As shown, a method of embedding convex defects in the first, second, and third deposited films 503, 504, and 508 using a multi-step process is effective.

Next, as shown in FIG.
Films (503, 504) formed as described above and projections
Condition defects 502 are simultaneously etched back at the same rate.
You. For example, the aforementioned 20 keV GaFIB and pyrene
Carbon film (503, 504) formed by gas and silicon acid
At the room temperature (25 ° C.)
When performing sputter etching with FIB, as shown in FIG.
Sea urchin C / SiO_TwoOf etch rate is GaFIB acceleration
It changes depending on the voltage, and at about 30 kV, C / SiO _TwoNo
The etch rate ratio is about 1. Therefore, under this condition,
Slightly larger than the convex defect 502 using the
Raster scan of the critical area and carbon and SiO2 simultaneously
It can be removed at one etching rate.

If the ratio of secondary ions of C and Si generated during this processing is measured using a mass spectrometer 506,
At the moment when the carbon around the convex defect 502 disappears in the beam scanning area, the secondary ion ratio of C / Si greatly changes,
It can be determined that the convex defect 502 has been cut to the same height as the surface of the substrate 501. Further, the end point can be determined using the secondary ion ratio of C / O instead of the secondary ion ratio of C / Si. A method of determining the end point of a process using such measurement of secondary ions is disclosed in, for example,
It is disclosed in JP-A-8-106750.

However, in the sputtering by GaFIB, a damage layer 507 having a depth of about 15 nm remains on the surface of the sputtered substrate 501, and reduces the transmittance of light used for exposure. Therefore, after the removal of the convex defects 502 is completed, for example, using XeF ₂ gas and GaFIB at room temperature (25 ° C.), as shown in FIG.
The damage layer 507 is assist-etched. Since a damaged layer cannot be formed by the assist etching using this gas, the substrate surface can be in a good state without damage. This processing results in a recess of about 15 nm, but such a recess does not transfer to the wafer and does not affect the surrounding pattern.

Finally, as shown in FIG.
The carbon remaining around when removing _TwoPlasma asher
To remove. For example, O_TwoGas in the chamber
Flow to 0.9 Torr and apply high frequency power 500W
Ashing by adding carbon without damage
Can be removed. Carbon removal is O_Twoplasma
Not only Usher, but O_TwoGas or CF_FourO with added
_TwoIt is also possible to carry out by CDE using gas. Further
In addition, it is more effective to maintain the substrate temperature at 150 to 400 ° C.
It is a target. Furthermore, O_TwoOr O_ThreeLaser illumination in atmosphere
This removal is also possible by irradiation or FIB irradiation.

It is efficient to remove the remaining carbon collectively after all the defects have been corrected. Also,
The order of the last two steps, the carbon removing step and the damage removing step, can be changed.

Here, the steps formed on the substrate surface when the convex defect is corrected by using the above-described repair process will be described. A step formed by the correction is obtained by adding a convex or concave step De formed by a difference between an etching rate of the flattening film and a defect to a sum of a concave amount y of the flattening film and a concave amount Dy generated by removing the damaged layer. Amount. Therefore, the level difference formed in this way must be suppressed to a level equal to or less than the level difference that causes a line width variation allowed in the transfer pattern.

Taking the Levenson type phase shift mask as an example, if an allowable value is 10% of the minimum resolution, a wavelength 2
48 nm, minimum dimension 0.25 μm, stepper NA = 0.
45, about 40 nm in the case of coherence factor σ = 0.3 showing coherence of exposure wavelength, wavelength 365 nm, minimum dimension 0.35 μm, NA of stepper = 0.46, coherence factor σ showing coherence of exposure wavelength In the case of = 0.3, it is about 80 nm. That is, if the amount of the step is less than the above, there is no problem in the transfer performance of the phase shift mask.
In other words, the processing conditions in each step can be reduced until (y + Dy + De) becomes the above-mentioned step. That is, if y = 10 nm and Dy = 15 nm at the wavelength KrF, the etching rate ratio (0.94 to 1.06) can be relaxed until De reaches a maximum of 15 nm.

As described above, if the convex defect is corrected according to the correction process flow of the present embodiment, the following effects can be obtained.

(1) Flattening films (first deposited film 503, second deposited film 504) are formed in a wider range than the convex defect 502.
Therefore, it is possible to minimize the occurrence of damage around the defect region caused by the irradiation of the Ga beam at the time of defect removal.

(2) Flattening films of different materials (503, 50)
4) and the convex defect are processed at the same time, and the secondary ions emitted from the planarizing film (C) and the defect (SiO ₂ ) or the ratio of the secondary ions are measured, so that the end point of the processing can be easily detected. .

(3) By flattening the convex defect 502 having a non-uniform thickness using the flattening films (503, 504), a flat shape after repair can be easily obtained.

(4) Damage layer 507 remaining on substrate 501
Can be easily removed by assist etching using XeF ₂ and GaFIB.

(5) The carbon film (50) used for defect removal
3, 504) can also be easily removed by the O ₂ plasma asher without damaging the others.

(6) Most repairs can be made by using a GaFIB device and only changing the type of gas introduced into the device, so that extremely efficient defect repair can be performed.

Although the process of repairing a convex defect has been described above, the repair process is not limited to the above example.

In the above example, a carbon film formed using pyrene gas as a raw material has been described as a flattening film covering a convex defect. However, a carbon film formed using another hydrocarbon gas as a raw material, such as W (CO) _6, is used. A tungsten film may be used. The coverage of the tungsten film was almost the same as that of the carbon film. When the above-described two-step deposition was performed at room temperature (25 ° C.), a flat film with a small dent in the surface could be obtained similarly to the carbon film. Further, in the simultaneous processing of the defect (SiO ₂ ) and the tungsten film, the point where the etching rate ratio becomes about 1 exists in the acceleration voltage range of a general FIB apparatus.

As a flattening film for covering the convex defect, F
Not only a film formed of IB but also a film made of a photosensitive resin or a resin crosslinked or decomposed by charged particles may be used. After applying these resins on the reticle by spin coating, using a microscope or the coordinates obtained in the inspection process, laser light only in the area containing the desired defect, light squeezed using a slit, Irradiate with FIB or electron beam. This is developed to form a flattening film. The formation of the first thin film and the second thin film is performed by repeating the above steps, and the film thickness is adjusted by adjusting the exposure amount (irradiation light amount) or the concentration of the resist when exposing the resist. When the convex defect is small or when the pattern is close to the defect to be corrected, it is only necessary to form the flattening film once. Thereafter, the same processing as the carbon film formed using FIB using the above-mentioned pyrene gas as a raw material can be performed. When a photosensitive resin or a resin which is crosslinked or decomposed by charged particles is used, it can be removed using a stripping solution such as a mixed solution of sulfuric acid and hydrogen peroxide.

Although the simultaneous etching of carbon and SiO ₂ is performed by GaFIB in the above example, FIB-assisted etching using gas is also possible. In this case, the etching rate of the deposited film and the shifter can be controlled by selecting and combining the gases. Furthermore, if a XeF ₂ mixed gas is used as a gas, no damage layer remains on the substrate surface when removing defects, and the damage layer removal step in the above-described process flow can be reduced, thereby eliminating the need for excavation. it can. In this case, there is a point in the general voltage range where the etching rate of carbon and SiO ₂ becomes about 1, and the absolute etching rate becomes larger than that in the case of sputter etching, so that the throughput can be improved. .

In the case of sputtering using GaFIB, for example, the sputtering yield of a quartz substrate becomes saturated with time (FIG. 6). This is because in sputtering, the sputtered material re-adheres around the processing area, and the sputtering yield saturates over time. On the other hand, in the assist etching using XeF ₂ gas and GaFIB, the etching yield of the quartz substrate is always constant because there is no effect of re-adhesion (FIG. 7), and there is an advantage that the controllability of processing is extremely good.

Although the removal of carbon remaining after the removal of the defect has been performed with an O ₂ asher in the above description, a laser beam may be used, for example. One method is to use the evaporation of carbon due to absorption of laser light.The laser light is finely squeezed using a slit, and when irradiating residual carbon, the laser energy is absorbed by carbon and becomes heat, which causes the sublimation and scattering of carbon. . At this time, absorption of laser energy also occurs in the damaged layer, and the damaged layer is removed in the same manner as carbon. The two steps of removing the residual carbon and removing the damaged layer are reduced to one step, and the repair process is more efficiently performed.

As another method, O_TwoOr O_ThreeAtmosphere
Carbon and O by laser light irradiation _TwoOr O_ThreeReact
CO, CO_TwoIs to be removed. This
In the case of using a chemical reaction, the laser
The power of the light can be reduced, and the light is
The light shield does not evaporate when irradiated with laser light, and only carbon is removed.
There are conditions that can be removed. Therefore, the beam diameter of the laser light
Tolerance, alignment tolerance, and process
There is an advantage that the margin is widened. In addition, laser light
When used, heating can be performed locally, so putter by heat
Distortion can be suppressed. Furthermore, O_TwoOr O_ThreeAtmosphere
The same effect can be obtained by using FIB instead of laser light.
Fruit can be expected. In this case, the choice of substrate material and carbon
Use light ions to obtain the ratio or use the acceleration energy
It is necessary to use FIB in which is set to 10 keV or less.

The deposition of carbon, simultaneous etching of carbon and SiO ₂ , and removal of the damaged layer are all performed by GaFIB, but are not limited to these ions. For example, it is apparent that the processes in the above steps may be performed using other ions such as Au and Si.

In addition, various modifications can be made without departing from the spirit of the present invention. In the above-described example, the repair method for the shifter made of silicon oxide has been described. However, the target to which the first and second defect repair methods are applied is not limited to the shifter made of silicon oxide. The present invention can also be applied to a shifter made of an organic material such as a resist, a shifter made of silicon or silicon nitride, or the like. In addition, the present invention can be applied to correction of a normal Cr mask or an X-ray mask.

(Example 6) In a sixth example, a method of correcting an irregular shifter concave defect that is not a rectangular parallelepiped by reducing surface irregularities will be described in detail with reference to FIG.

First, based on information such as the size, shape (convex or concave), film thickness, and position of a defect obtained using a general defect inspection apparatus, a defect to be corrected using a FIB apparatus is used. Recognize. After the concave defect 602 is confirmed in the phase shifter 601, a silicon oxide film is formed so as to slightly protrude from the surface of the shifter 601 using the gas sprayed from the nozzle and the FIB.

At this time, the FIB is so formed as to cover the entire concave defect.
In order to fill a concave defect having a complicated shape as shown in FIG. 17 (A), it is necessary to protrude and deposit significantly larger than the surface of the shifter. is not. Therefore, multi-stage deposition is performed to reduce surface irregularities. Based on the information about the defect shape obtained by the defect inspection apparatus, the first silicon oxide film 603 is formed at appropriate intervals so as to be substantially the same height as the substrate surface as shown in FIG. Form.

Next, as shown in FIG. 17C, a second silicon oxide film 604 is formed in a region covering the concave defect 602 and the first silicon oxide film 603. In the assist deposition using an ion beam and a gas, deposition proceeds due to ions and secondary electrons scattered multiplely inside the narrow groove, so that the film forming speed is higher inside the groove than on the first silicon oxide film 603. It becomes faster, and the unevenness of the surface becomes smaller, and a flat film can be obtained.

In the above description, the concave defect is buried in the silicon oxide film in two steps. However, when the concave defect is severe as shown in FIG. 18A, the concave defect is formed as shown in FIGS. 18B to 18D. First, the second, third, and fourth silicon oxide films (deposited films) 603, 6
The method of embedding at 04,610,612 is effective.

The silicon oxide film is formed of a gas having a Si—O bond and / or a Si—H bond, or a mixed gas containing the same, for example, a mixed gas of 1,3,5,7-tetramethylcyclotetrasiloxane and oxygen. (Mixing ratio = 1: 7) while blowing at room temperature (25 ° C.) at 50 keV Si ²⁺ FIB
Is formed by irradiation. The diameter of the nozzle used here is 0.2
mm, the pressure with the capacitance type pressure gauge shown in FIG. 1 was 4 Torr. At this time, the total flow rate of the gas at the nozzle outlet is 0.
It was 05 sccm.

The light transmittance of the thus formed silicon oxide film having a thickness of 0.4 μm at a wavelength of 436 nm is 10 μm.
0%, which is better in optical characteristics than the conventional film formed using a mixed gas of tetramethoxysilane and oxygen having a light transmittance of 40%. Further, the light transmittance of the silicon oxide film formed by the method of the present embodiment with respect to light having a wavelength of 248 nm (light used in the Levenson-type phase shift mask method) is 90.6%, which is the light required for correcting a concave defect. It has a value equal to or higher than the transmittance (80.6%).

When it is necessary to improve the light transmittance of the deposited film, the following post-processing may be performed. UV whose power density on the deposited film surface is 200 mW / cm ² after film formation
A process of irradiating light for one hour is performed. Also, such UV
Even if the film is formed while irradiating UV light instead of the light treatment, a deposited film having the same light transmittance can be obtained, and the other formed film is annealed at 350 ° C. for 1 hour in an O ₂ atmosphere. The same effect can be obtained.

Here, the above two types of gases may be sprayed from separate nozzles, respectively, and O ₃ ,
A gas containing oxygen as a main component such as N ₂ O may be used. The gas mixture ratio is not limited to 1: 7,
The mixing ratio may be set such that the deposit is transparent according to the ion species and energy of B and no cavity is formed inside. For example, TEO
When S is used, at the room temperature, "spot" is formed inside the deposit, but when the mask temperature is lowered to about -70 degrees, the "spot" is not formed and the concave defect can be filled. FI
The energy and ion species of B are 50 keV Si ²⁺ FIB
Not only that, other energies and ion species such as 25 keV Ga ⁺ FIB can be selected. Also,
An electron beam may be used instead of the FIB.

However, when the charge nutrizer is near the gas nozzle and the radiation heat from the electron emission filament in the nutrizer affects the gas, black contamination made of carbon adheres to the mask substrate. Therefore, it is desirable that the charge nut riser be arranged away from the gas nozzle.

Next, as shown in FIG. 17D, the first flattening film 605 is formed in a donut shape with a slight space around the protrusion of the silicon oxide film (603, 604). 603, 604). The planarization film 605 is formed by assist deposition in which pyrene gas is decomposed by, for example, GaFIB accelerated to 20 keV to deposit carbon (C).

Next, as shown in FIG. 17E, a silicon oxide film (603, 604) and a first planarizing film 605 are formed.
A second planarizing film 606 is formed in a region covering the semiconductor substrate. At this time, the distance x between the protrusion of the silicon oxide film and the first planarization film 605 and the depth y of the surface dent generated when the second planarization film 606 is formed with a thickness of 1.0 μm. There is a relationship between them as shown in FIG. That is, y decreases as x decreases. This is because, in the assist deposition using an ion beam and a gas, the deposition proceeds due to ions and secondary electrons scattered multiplely inside the narrow groove, so that the protrusions of the silicon oxide films (603, 604) and the first planarization Membrane 6
This is because the film forming speed is higher inside the groove than on the surface 05, and y is small, so that a flat film can be obtained.

In the above description, the concave defect portion is flattened in two stages. However, if the concave defect is severely uneven, the concave defect is embedded in one or two stages, and then the multi-step process shown in FIG. It is also effective to flatten the concave defect portion by using.

Next, as shown in FIG. 17F, the flat films (605, 606) and the silicon oxide films (603, 604) thus formed are simultaneously etched at the same rate. For example, the aforementioned 20 keV G
Carbon film formed using a FIB and pyrene gas (60
5, 606) and a protrusion (60) made of a silicon oxide film.
3, 604) is sputter-etched with GaFIB, as shown in FIG. 5, the etching rate ratio of C / SiO ₂ changes depending on the acceleration voltage of GaFIB.
At 0 kV, the etching rate ratio of C / SiO ₂ becomes about 1. Therefore, under this condition, the area slightly larger than the protrusions (603, 604) made of the silicon oxide film is raster-scanned by using the beam 607 narrowly narrowed, and the carbon and the silicon oxide film are simultaneously removed at the same etching rate. it can.

If the ratio of the secondary ions of C and Si generated during this processing is measured using a mass spectrometer 608,
Silicon oxide film (603, 604) in the beam scanning area
At the moment when the carbon around the silicon disappears, the secondary ion ratio of C / Si greatly changes.
It can be determined that it has been cut to the same height as the surface. Also C
Instead of the secondary ion ratio of / Si, the end point can be determined using the secondary ion ratio of C / O. A method for determining the end point of the process using such measurement of secondary ions is disclosed in, for example, Japanese Patent Application Laid-Open No. 58-106750.

However, in sputtering by GaFIB, the surface of the sputtered substrate has a depth of 15 nm.
Some damage layer 609 remains, and lowers the light transmittance used for exposure. Therefore, the silicon oxide film (603,
After the removal of 604) is completed, the damaged layer 609 is assist-etched using, for example, XeF ₂ gas and GaFIB as shown in FIG. Since the damaged layer does not remain in the assist etching using this gas, the substrate surface can be brought into a favorable state without damage. This processing results in a recess of about 15 nm, but such a recess does not transfer to the wafer and does not affect the surrounding pattern.

Finally, as shown in FIG. 17H, carbon remaining around the silicon oxide films (603, 604) at the time of removal is removed by an O ₂ plasma asher.
For example, when ashing is performed by flowing O ₂ gas so that the inside of the chamber becomes 0.9 Torr and applying a high frequency power of 500 W, carbon can be removed without damage. The removal of the carbon does not become O ₂ plasma asher only, it is possible to perform even CDE using O ₂ gas or CF ₄ O ₂ gas was added. Further, it is effective to keep the substrate temperature at 150 to 400 ° C. Further, carbon can be removed by laser irradiation or FIB irradiation in an O ₂ or O ₃ atmosphere.

It is more efficient to remove the remaining carbon collectively after all defects have been corrected. Also, the order of the last two steps, the carbon removing step and the damage removing step, can be changed.

As described above, if the defect is corrected in accordance with the present repair process flow, the following effects can be obtained.

(1) The concave defect 602 is formed by a silicon oxide film (6
03, 604), it is not necessary to embed them in the shape of the dent, so that the process becomes extremely simple.

(2) The protrusion caused by the embedding of the concave defect 602 has a flattening film (60
5,606), the Ga is removed when the protrusion is removed.
Damage to the periphery of the defect area caused by the beam irradiation can be suppressed as much as possible.

(3) Flattening films of different materials (605, 60
6) and the silicon oxide films (603, 604) are processed simultaneously, and the secondary ions emitted from the flattening film (C) and the protruding portion (silicon oxide film) or the ratio of the secondary ions is measured, thereby protruding. It is easy to detect the end point of the part machining.

(4) Since the protrusions having an irregular thickness are also flattened by using the flattening films (605, 606), the repair surface is easily flattened.

(5) The damaged layer 609 remaining on the surface of the corrected concave defect can be easily removed by assist etching using XeF ₂ and GaFIB.

(6) The carbon film used for defect repair is also O
₂ It can be easily removed by plasma asher without damaging others.

(7) Since most repairs can be made by using a GaFIB device and changing only the type of gas introduced into the device, extremely efficient defect repair becomes possible.

Although the repair process of the concave defect has been described above, the repair process is not limited to the above example.

In the above example, a carbon film using pyrene gas as a raw material is described as a planarizing material for covering a protruding portion remaining after a concave defect is buried with a silicon oxide film. However, the same modification as in the first example is possible. .

As for the simultaneous etching of carbon and SiO ₂ , the same modification as in the first example is possible. Further, the removal of carbon remaining after the removal of the protruding portion can be modified in the same manner as in the first example. Also, carbon deposition, carbon,
An ion source used for simultaneous etching of SiO ₂ and removal of a damaged layer can be modified in the same manner as in the first example.

The process can be omitted depending on the shape of the concave defect. That is, FIGS.
After the formation of the silicon oxide film in multiple stages as shown in FIG. 17C, the irregularities on the surface are within the steps allowed for defect correction depending on the shape of the concave defect. There is no need to proceed.

In the above example, the concave defect is buried with a silicon oxide film, but the burying material is not limited to silicon oxide. The embedding material should be selected depending on the material of the shifter, and the above-mentioned correction can be similarly performed for silicon nitride, chromium oxide, and the like.

(Example 7) In a seventh example, a method for repairing a shifter concave defect will be described, particularly including the effect of improving the film quality of an embedded material deposited on the concave defect.

This example is basically the same as the second example. An SiO ₂ film 706 is formed in the same manner as the steps shown in FIGS. Second deposited films 707 and 708 are formed. Thereafter, the area covered with the first and second deposited films 707 and 708 is irradiated with laser light, and the SiO ₂ film 706 below the deposited films 707 and 708 is locally heated by heat generated by energy absorption of the carbon film. I do. In the SiO2 film 706, defects in the SiOx structure are improved by an annealing effect by heating, and the light transmittance of the SiO2 film is improved. In this case, an improvement in light transmittance as shown in FIG. 19 is recognized. After this, FIG.
8G, the etch back of the SiO ₂ film 706 and the deposited films 707 and 708, the damage layer 2
11 is removed.

As described above, when the concave defect is corrected in accordance with the correction process flow of the present embodiment, it is described in the second example (1)
In addition to the effects of (7), the structural defect of the SiO ₂ film 706 is improved by laser annealing, and the effect that the light transmittance of the SiO ₂ film 706 can be improved can be obtained.

First, based on information such as the size, shape (convex or concave), and position of a defect obtained using a general defect inspection device, a defect to be corrected is recognized using an FIB device. . As shown in FIG. 20A, after a concave defect 702 is confirmed in the phase shifter 701, a gas having a Si—O bond and / or a Si—H bond from the nozzle 703 on the concave defect 702 at room temperature, or Mixed gas containing, for example, 1,
While spraying a mixed gas 704 (mixing ratio = 1: 7) of 3,5,7-tetramethylcyclotetrasiloxane and oxygen, the GaFIB 70 is applied to a region slightly larger than the concave defect 702.
Irradiate 5 As a result, as shown in FIG. 20B, an SiO ₂ film (embedding material) 706 slightly projecting from the surface of the shifter 701 is formed. The diameter of the nozzle used was 0.2 mm, and the pressure measured by the capacitance type pressure gauge shown in FIG. 1 was 4 Torr. At this time, the total flow rate of the gas at the nozzle outlet was 0.05 sccm.

FIG. 23 shows the relationship between the energy of the GaFIB to be irradiated and the light transmittance of the formed SiO ₂ film (thickness: 0.3 μm) to 248 nm light (light used for the Levenson-type phase shift mask). The light transmittance increases as the energy of GaFIB decreases. This is S
During the formation of the iO ₂ film, Ga ⁺ ions are implanted into the deposited film to cause a defect that causes a decrease in light transmittance. As the energy of the Ga ⁺ ion is smaller, the defect generated per ion is smaller. This is because the number decreases. Here, Ga
Since the energy of the FIB was 5.5 keV, the light transmittance of the formed film was 91%, which is a value higher than the light transmittance (80.6%) required for correcting the concave defect.
The beam current of GaFIB was 20 pA. Here, since a retarding mode FIB apparatus, that is, an apparatus capable of setting the voltage of the sample stage to 19.5 kV with an acceleration voltage of 25 kV, is used, the irradiation energy of Ga ⁺ ions [(acceleration voltage) − (sample stage voltage) ] × e (elementary charge) is 5.5 keV, the beam diameter is 0.05 μmφ, and a film can be formed in a fine region. The acceleration voltage is 5.5 in a normal FIB device instead of in the retarding mode.
kV, and the beam diameter in this case is ~
1 μm, making it difficult to form a film on a fine region.

In this case, the Ga ⁺ FI of 5.5 keV is used.
Although B is used, other energies can be selected in consideration of the relationship between the energy of Ga ⁺ ions and the light transmittance in FIG. 23, and other ion species can also be selected. The two types of gases may be sprayed from separate nozzles, or a gas containing oxygen as a main component such as O ₃ or N ₂ O may be used instead of oxygen. The mixture ratio of the gas is not limited to 1: 7, and the mixture ratio may be such that the deposit is transparent and the concave defect is filled in a good shape according to the type of gas used, the ion type of FIB, and the energy.

When the charge nutrizer is near the gas nozzle and the radiation heat from the electron emission filament in the nutrizer affects the gas, black contamination made of carbon adheres to the mask substrate. Therefore, it is desirable to dispose the charge nut riser away from the gas nozzle.

Next, as shown in FIG.
A first thin film 707 is formed in a donut shape to the same height as the SiO ₂ film 706 around the protrusion of the O ₂ film 706 at a slight interval. This deposited film 707 is, for example, 20 k
It is formed by assist deposition in which pyrene gas is decomposed by GaFIB accelerated to eV to deposit carbon (C).

Next, as shown in FIG.
A _second deposited film 708 is formed in a region covering the projected portion of the O ₂ film 706 and the first deposited film 707. SiO _{2 at} this time
The distance between the distance x between the projecting portion of the film and the first deposited film 707 and the depth y of the dent on the surface generated when the second deposited film 708 is formed to have a thickness of 1.0 μm is shown in FIG. There is a relationship as shown in FIG. That is, y decreases as x decreases.
This is because, in assist deposition using an ion beam and a gas, deposition proceeds by ions and secondary electrons scattered multiplely inside a narrow groove, so that the protrusion of the SiO ₂ film 706 or the first deposition film 707 This is because the film forming speed becomes higher inside the groove, y becomes smaller, and a flat film can be obtained.

Next, as shown in FIG. 20E, the flat films (707, 708) thus formed and S
The protrusions of the iO ₂ film 706 are simultaneously etched at the same rate. For example, the above-mentioned 20 keV GaFIB
Films (707, 70) formed by using
8) and when the protrusion of the SiO ₂ film 706 is sputter-etched with GaFIB, as shown in FIG.
The etching rate ratio of O ₂ changes depending on the acceleration voltage of GaFIB, and the etching rate ratio of C / SiO ₂ becomes about 1 at about 30 kV. Therefore, under this condition, an area slightly larger than the protruding portion can be raster-scanned by using the beam 709 narrowly narrowed, thereby simultaneously removing C and SiO ₂ at the same etching rate.

When the ratio of the secondary ions of carbon and Si generated during this processing is measured using a mass spectrometer 710, the carbon around the protrusion of the SiO ₂ film 706 in the beam scanning area is reduced. Since the secondary ion ratio of C / Si greatly changes at the moment of disappearance, it can be determined that the protrusion of the SiO ₂ film 706 has been cut to the same height as the surface of the shifter 701.
Further, it is also possible to determine the end point using the secondary ion ratio of C / O instead of the secondary ion ratio of C / Si.

However, in sputtering by GaFIB, the surface of the sputtered substrate has a depth of 15 nm.
Some damage layer 711 remains, and lowers the light transmittance used for exposure. Therefore, after the removal of the protruding portion of the SiO ₂ film 706 is completed, as shown in FIG. 20F, the damaged layer 7 is formed using, for example, XeF ₂ gas and GaFIB.
11 is assist-etched. Since the assist layer using this gas does not leave the damaged layer 711,
The damage layer 711 can be removed. Although this processing results in a recess of about 15 nm, such a recess does not transfer onto the wafer and does not affect the surrounding pattern.

Finally, as shown in FIG.
The carbon remaining around the protrusion of the O ₂ film 706 is removed by an O ₂ plasma asher. For example, O ₂
When ashing is performed by flowing a gas so that the pressure in the chamber becomes 0.9 Torr and applying a high frequency power of 500 W, carbon can be removed without damage. Carbon removal is
O ₂ not plasma asher only, it is possible to perform even CDE using O ₂ gas or CF ₄ O ₂ gas was added. Further, it is more effective to keep the substrate temperature at 150 to 400 ° C. Further, carbon can be removed by laser light irradiation or FIB irradiation in an O ₂ or O ₃ atmosphere.

It is more efficient to remove the remaining carbon collectively after all the defects have been corrected. Also, the order of the last two steps, the carbon removing step and the damage removing step, can be changed.

As described above, if the concave defect is corrected according to the correction process flow of the present embodiment, the following effects can be obtained.

(1) Since it is not necessary to bury the concave defect 702 in the SiO ₂ film 706 in the shape of the concave, the process becomes extremely simple.

(2) The protruding portion caused by the embedding of the concave defect 702 is covered with the planarizing films (the first deposited film 707 and the second deposited film 708) over a wider range. At the time of removing the portion, it is possible to minimize the occurrence of damage to the periphery of the defective region caused by the Ga beam irradiation.

(3) Flattening films (707, 70) of different materials
8) and the protruding portion of the SiO ₂ film 706 are simultaneously processed, and the secondary ions emitted from the planarizing film (C) and the protruding portion (SiO ₂ ) or the ratio of the secondary ions is measured, thereby processing the protruding portion. Is easy to detect.

(4) Since the protrusions having an irregular thickness are also flattened using the flattening films (707, 708), the repair surface is easily flattened.

(5) The damaged layer 711 remaining on the surface of the corrected concave defect can be easily removed by assist etching using XeF ₂ and GaFIB.

(6) The carbon film (70) used for defect repair
7, 708) can also be easily removed by the O ₂ plasma asher without damaging the others.

(7) Since most repairs can be made by using a GaFIB device and changing only the type of gas introduced into the device, extremely efficient defect repair becomes possible.

(8) Since the acceleration energy of Ga ⁺ ions is reduced, the light transmittance of the SiO ₂ film 706 deposited in the concave portion can be sufficiently increased even for a short wavelength (248 nm). The present invention can be applied to the modification of the Levenson type phase shift mask used in the above wavelength region.

Although the process of repairing a concave defect has been described above, the repair process is not limited to the above example.

In the above example, the carbon film formed by using pyrene gas as a raw material as a flattening film covering the protrusions remaining after the concave defects are buried with SiO ₂ has been described. Film or, for example, W (C
O) A tungsten film formed using ₆ can also be used. The coverage of the tungsten film was almost the same as that of the carbon film. When the above-described two-step deposition was performed, a flat film with small dents on the surface could be obtained similarly to the carbon film. Further, in the simultaneous processing of the protrusion (SiO ₂ ) and the tungsten film, the point where the etching rate ratio becomes about 1 exists in the acceleration voltage range of a general FIB apparatus.

As the flattening film covering the convex defect,
Not only a film formed by FIB but also a film made of a photosensitive resin or a resin crosslinked or decomposed by charged particles may be used. When these films are formed, these resins are applied on a reticle by spin coating, and then a laser beam or a slit is applied only to a region containing a desired defect using a microscope or by using coordinates obtained in an inspection process. Is used to irradiate a focused beam, FIB or electron beam. Then
This is developed to form a flattening film. The formation of the first thin film and the second thin film is performed by repeating the above steps, and the film thickness is adjusted by adjusting the exposure amount (irradiation light amount) or the concentration of the resist when exposing the resist. When the convex defect is small or when the pattern is close to the defect to be corrected, it is only necessary to form the flattening film once. Hereinafter, F
Processing similar to that of a carbon film formed using IB can be performed. When a photosensitive resin or a resin which is crosslinked or decomposed by charged particles is used, it can be removed using a stripping solution such as a mixed solution of sulfuric acid and hydrogen peroxide.

[0214] Also, carbon, as the simultaneous etching of SiO _2, it is possible modified as the first example. further,
The same modification as in the first example can be applied to the removal of carbon remaining after the removal of the protrusion. Also, carbon deposition, carbon, Si
An ion source used for simultaneous etching of O ₂ and removal of the damaged layer can be modified in the same manner as in the first example.

In the above process, the shape of the concave defect is reduced.
We did not describe it, but we could omit the process depending on the shape.
Can be abbreviated. That is, a concave shape with a large aspect ratio
In the case of a defect, 1,3,5,7-tetramethylcyclotet
SiO using lasiloxane _TwoFig. 21
(A). In such a case, unevenness on the surface
20 is within the level allowed for defect repair,
(C) It is not necessary to proceed with the steps described below.

On the other hand, FIG. 21 (B) and FIG. 21 (C)
In the case of a defect as indicated by, the unevenness of the surface after depositing SiO ₂ does not fall within an allowable step, so that all the steps shown in FIG. 20 are required. Furthermore, if defects such as FIG. 21 (C), the slightly apart by depositing SiO ₂ from the side wall in the previously recessed as shown in FIG. 22, the SiO ₂ followed completely cover the defect area By depositing
Deposition with small surface irregularities can be performed. In this case, it may not be necessary to proceed with the steps shown in FIG. 20C and thereafter, as described above.

In the above example, silicon oxide has been described, but the present invention is not limited to silicon oxide.
For example, by lowering the FIB energy to be irradiated when forming a film even with silicon nitride, Cr oxide, or the like,
A decrease in light transmittance due to ion irradiation can be suppressed.

In addition, various modifications can be made without departing from the spirit of the present invention.

[0219] In each of the above-described examples, the repair method has been described using the phase shift mask as an example. However, the application of the first and second defect repair methods is not limited to the phase shift mask. The present invention can be applied to correction of a normal Cr mask or X-ray mask. Further, it can be applied to the modification of a Fresnel zone plate and other optical components.

(Example 9) In the ninth example, a method of repairing a shifter concave defect is described in detail with reference to an S-filling material deposited on the concave defect.
The formation of the iO ₂ film will be described.

This example is basically based on Japanese Patent Application No. 4-2945.
This is the same as the second embodiment in the specification of No. 36. First, based on information such as the size, shape (convex or concave), and position of a defect obtained using a general defect inspection device,
The defect to be corrected is recognized using the FIB device. After a concave defect is confirmed in the phase shifter, a gas having a Si—O bond and / or a Si—H bond or a gas containing the same, for example, 1,3,5,7-tetra While blowing a mixed gas of methylcyclotetrasiloxane and oxygen, Ga ⁺ F
Irradiate IB. Thus, an SiO ₂ film (embedding material) slightly projecting from the shifter surface is formed. The diameter of the nozzle used here was 0.2 mm, and the total gas flow rate at the nozzle outlet was 0.05 sccm.

According to the specification of Japanese Patent Application No. 4-294536, in order to improve the light transmittance of the SiO ₂ film as the burying material, the deposited film is irradiated with UV light or is formed while being irradiated with UV light. Or annealing of the deposited film in an O ₂ atmosphere or deposition with low energy ions. In the case of a SiO ₂ film formed using 50 keV Si ²⁺ FIB, the light transmittance was improved by annealing treatment in an O ₂ atmosphere, but 25 keV Ga ⁺
In the case of a SiO ₂ film formed using FIB, the effect of improving the light transmittance by annealing in an O ₂ atmosphere cannot be obtained. Further, the annealing process in the process of correcting the Levenson-type phase shift mask may cause a problem such as distortion of the mask pattern.

On the other hand, in the case of using low energy ions, if the FIB apparatus in the retarding mode is used, the beam diameter is 0.05 μmφ even when the ion energy is 5.5 keV. Is possible, but the ion energy is 5.
In the case of 5 keV, the beam diameter becomes 1 μmφ, and it is difficult to form a film in a fine region. At 5.5 keV, the film formation efficiency is low, so that it is not very practical. In this example, G
with a ⁺ FIB, energy other than ion energy 5.5KeV, yet show an example of forming a SiO ₂ film having a light transmittance that can be used to modify the phase shifter without post-treatment such as annealing or UV irradiation .

In this example, the SiO ₂ film was formed by irradiating Ga ⁺ FIB with a mixed gas of 1,3,5,7-tetramethylcyclotetrasiloxane (TMCTS) and oxygen as a material gas for film formation. I went by. FIG. 24 shows the relationship between the beam current density at an ion energy of 25 keV and the light transmittance of the formed SiO ₂ film to KrF light (wavelength: 248 nm).

As can be seen from FIG. 24, the light transmittance tends to increase as the beam current density decreases, but the light transmittance saturates at a beam current density of 11 mA / cm ² or less. This saturation tendency is the same regardless of the ion energy. Therefore, film formation was performed using a beam having a beam current density at which the light transmittance was saturated at each ion energy.

Next, FIG. 25 shows the light transmittance of the SiO ₂ film (250 nm thick) with respect to KrF light (wavelength 248 nm) when the ion energy and the O ₂ partial pressure ratio were changed. According to this, there is a tendency that the O ₂ partial pressure ratio with respect to TMCTS is high, and / or the light transmittance is higher as the ion energy is lower.

In the Levenson-type phase shift mask for KrF light, the thickness t of the phase shifter for inverting the phase is t = λ / ｛2 where λ is the wavelength of the exposure light source and n is the refractive index.
It is represented by an odd multiple of (n-1)｝. Here, since KrF is used as the light source (λ = 248 nm) and the phase shifter is a silicon oxide film (n = 1.508), t = 244 nm. According to the simulation, it has been found that the light transmittance for KrF light required for correcting the concave defect of the shifter of the Levenson-type phase shift mask for KrF light may be 80% or more. Therefore, the SiO ₂ film may be formed under the condition of a partial pressure ratio equal to or higher than the curve showing the light transmittance for KrF light of 80% in FIG.

According to this method, even if ions of any energy are used in a normal FIB apparatus, Si
An O ₂ film can be formed. Note that the light transmittance is 7
If it is 0%, may be performed deposition at curves or more O ₂ voltage dividing ratio showing 70% of 25, also in the case of other light transmission ratio O ₂ minutes in the light transmittance The SiO ₂ film may be formed in a region at or above the O ₂ partial pressure ratio determined from the relationship between the O ₂ and the ion energy.

The subsequent steps are described in Japanese Patent Application No. 4-294536.
In the same manner as in the step shown in Example 2 of Pat, SiO ₂
The film and the first and second thin films are etched back.

As described above, if the concave defect is corrected in accordance with the correction process flow of the present example, Japanese Patent Application No. 4-2945 is disclosed.
In addition to the effects (1) to (7) described in the 36th embodiment, it is possible to efficiently form SiO ₂ having a high light transmittance which can be used for correcting a phase shifter concave defect of a phase shift mask without post-processing. Is obtained.

Here, the TMCT used in this example
S will be described. First of all, TMCTS is a
As shown in FIG. 7 (A), it is a cyclic molecule having a bond of —Si—O—Si—. TMCTS-
The Si—O—Si— bond is stable, and the Si—O—Si— bond is easily retained to form the SiO ₂ film shown in FIG. This is because the ethoxy group O is relatively reactive and is easily desorbed as ethanol.
Is significantly different from TEOS bonded to Si.

Second, in TMCTS, as shown in FIG. 27A, in addition to the Si—O bond and the Si—C bond,
There is an iH bond. This is, as shown in FIG. 27B, an OMCT consisting only of Si—O bonds and Si—C bonds.
Unlike S (octamethylcyclotetrasiloxane), TMCT
When a film is formed by using S, since steric hindrance due to a bulky CH ₃ group is small, O atoms easily react with Si atoms and Si—
O bonds are likely to occur. As described above, the SiO ₂ film obtained by using TMCTS is made of the Si ₂ film obtained by using OMCTS.
Light transmittance is higher than O ₂ film.

Third, the SiO2 layer made of GaFIB_TwoFilm formation
The membrane yield is 7 atom / ion when using TMCTS.
In the case where TEOS is used, it is 2 atom / ion. did
Therefore, when TMCTS is used, it is possible to achieve a specific film thickness.
During film formation, the number of incident ions is small.
Damage due to incident ions is small, resulting SiO _Two
The light transmittance of the film increases.

(Example 10) In a tenth example, formation of a flattening film covering a convex defect and removal of the flattening film and a residual flattening film after the etching of the convex defect will be described. Japanese Patent Application No. 4
According to -294536, the first and second films are planarized by using a carbon film assisted by FIB. In this example, FI is used as a flattening film.
An example in which the residual flattening film is removed by wet etching using Au deposited assisted by B will be described.

First, based on information such as the size, shape (convex or concave), and position of a defect obtained by using a general defect inspection apparatus, a defect to be corrected using an FIB apparatus is recognized. I do. After the concave defect was confirmed, Ga of 15 keV was used.
⁺ FIB and a source gas for forming an Au film, for example, dimethyl gold hexafluoroacetylacetonate (C
Au is deposited by assist deposition using ₇ H ₇ F ₆ O ₂ Au) so that the upper portion of the convex defect becomes flat. At this time, as shown in Japanese Patent Application No. 4-294536, flattening is performed by two-step or multi-step deposition depending on the shape and position of the defect.

After the deposition of the flattening film, the structure is disclosed in Japanese Patent Application No. 4-29453.
In the same manner as in the process described in the specification of No. 6, 30 keV Ga
Using a FIB and XeF ₂ gas, a flat region of the Au film including a convex defect is removed. Here, Au is GaFIB
Is removed by sputtering with a convex defect (Si
O ₂ ) is removed without a decrease in light transmittance by the assisted etching of GaFIB and XeF ₂ . At this time, XeF ₂
The etching rates of Au and SiO ₂ are made equal by adjusting the gas pressure of the above.

Excessive peeling of the Au film after etch-back
This is performed by wet etching using aqua regia. Au dissolves in aqua regia, whereas Si, the material of the mask shifter, is used.
Since O2 and chromium or chromium oxide, which is a light shielding member, are insoluble in aqua regia, only Au can be peeled off without damaging the light shielding member and the shifter.

As a substance soluble in aqua regia, Pt besides Au is used.
Therefore, instead of the Au film, there is a flattening film that covers the convex defects.
Then, a source gas for FIB and Pt film deposition, for example,
(Methylcyclopentadimethyl) trimethyl platinum
[(MeCp) PtMe_ThreeThe Pt film deposited using
May be used. Other mask light shields and shifters
Uses a material that dissolves in insoluble chemicals as a flattening film
It is also possible. In addition, the method of the present example has a concave defect.
Deposited slightly protruding from the surface of the shifter _Twofilm
(Filling material) can be used in the process of flattening
it is obvious.

(Example 11) In an eleventh example, removal of a flattening film covering a convex defect will be described. In particular, the use of a mixed gas of a hydrocarbon gas and a hydrogen gas as the source gas for the planarization film will be described.

In the specification of Japanese Patent Application No. 4-294536, pyrene, styrene, methyl methacrylate, 2,2
Although it has been described that a hydrocarbon gas such as 4,4-trimethyl-1-pentene and isoprene is used, a mixed gas of a hydrocarbon gas and a hydrogen gas may be used as a raw material gas. By mixing hydrogen gas, the amount of hydrogen in the carbon film increases, and the polymerization of the carbon film proceeds. Thereby, removal of the carbon film can be facilitated. This can be understood from a comparison between a carbon film formed by sputtering or the like and a resist which is a polymer, because the resist can be more easily removed by asher, CDE, laser or the like.

For example, 2,4,4-hydrocarbon gas
The case where trimethyl-1-pentene gas and hydrogen gas are used will be described. In the apparatus shown in FIG.
A 4,4-trimethyl-1-pentene gas and a hydrogen gas are charged into a gas cylinder 11, and 1.0 Torr of 2,4,4-trimethyl-1-pentene and 1.0 Torr of hydrogen gas are introduced in a gas introduction system.
Are sprayed onto the surface of the sample 8 from the nozzle 13. Here, the beam current 10 p extracted from the Ga ion source 1
A, FIB was irradiated at an acceleration voltage of 25 keV to form a carbon film. The deposition efficiency of the carbon film thus formed is 18
atom / ion, which was 1.6 times that of 2,4,4-trimethyl-1-pentene alone. The carbon film was subjected to a power of 1 using 20 sccm of water and 200 sccm of oxygen gas.
When the carbon film was removed by CDE at 00 W, the removal rate was improved by a factor of 5 as compared with a carbon film formed using only 2,4,4-trimethyl-1-pentene gas as a source gas. Here, the mixing ratio of 2,4,4-trimethyl-1-pentene gas and hydrogen gas was set to 1: 1. However, when the total pressure was kept constant, the removal rate of the carbon film formed by increasing the hydrogen gas partial pressure was reduced. On the other hand, if the gas partial pressure is too high, the film forming efficiency is lowered. Therefore, it is desirable to select appropriate conditions for the hydrogen gas partial pressure.

(Example 12) In a twelfth example, removal of a flattening film covering a convex defect will be described. In particular, the Ga removal step will be described.

In the step of removing the carbon film in the specification of Japanese Patent Application No. 4-294536, O
₂ alone, O ₃ alone, or O ₂ and N ₂ , H ₂ O, CF ₄ ,
CDE using mixed gas with H ₂ , N ₂ O or NO
When removing carbon by laser irradiation or the like in an O ₂ or O ₃ atmosphere, it is preferable to include a Ga removal step.

A carbon film formed by FIB assisted deposition contains not only carbon but also Ga and O. Therefore, in the above-described method of oxidizing and removing carbon, carbon is removed as CO and CO ₂ , but Ga is not removed by oxidation but remains as gallium oxide on the surface layer. Therefore, as the etching of the carbon film proceeds, the concentration of Ga on the surface of the carbon film increases, and the etching rate decreases. If the carbon film whose etching rate has dropped is left for 5 minutes together with the reticle in, for example, a 1N aqueous nitric acid solution, gallium oxide remaining on the surface of the carbon film is removed. Thereafter, by performing CDE or laser irradiation utilizing the oxidation of carbon, etching can be favorably performed. In this case, the quartz substrate is insoluble in nitric acid,
Cr, which is a light shield, and CrOx, which is an antireflection film, passivated nitric acid, and thus were insoluble, and did not damage the reticle. For removal of gallium oxide by such wet etching, not only nitric acid but also alkali such as concentrated sulfuric acid, KOH and NaOH can be used.

(Example 13) In a thirteenth example, a description will be given of deposition of a flattening film covering a convex defect and removal of a residual flattening film after etch-back. That is, in this example, a thin film that is easy to remove with a solution is formed as a flattening film, a carbon film is formed thereon to form a two-layer film, and after etching back, the carbon remaining in the solution together with the lower layer film is removed. An example in which the film is removed will be described.

First, based on information such as the size, shape (concave or convex), and position of a defect obtained using a general defect inspection apparatus, PIBM (polyisobutyl) is added to a region including a convex defect. A LB (Langmuir Blodgett) film of methacrylate) is formed (18 layers, thickness of 200 Å). Next, a defect to be corrected is recognized using the FIB apparatus based on the information on the defect. After the convex defect was recognized, it was subjected to 5 keV GaFIB using pyrene gas.
A carbon film is formed with a thickness of 200 angstroms on the LB film including the region where the flattening film is to be formed. Next, as described in Japanese Patent Application No. 4-294536, a 20 keV G film is formed using pyrene gas in order to accurately form a flattening film.
In the aFIB, two-stage or multi-stage deposition is performed according to the shape and position of the defect, and thereby the surface is planarized. Where 5
Since the range of keV Ga ions in the LB film is within 100 Å, the structure of the LB film is not completely destroyed by the implantation of Ga ions into the LB film. In addition, by forming a carbon film using GaFIB of 5 keV, G is formed by forming a carbon film using GaFIB of 20 keV thereafter.
The a ion does not completely destroy the structure of the LB film.

After the formation of the flattening film, Japanese Patent Application No. 4-294.
In the same manner as in the process described in the specification of Japanese Patent No. 536, a flat region of a carbon film including a convex defect is removed. After the etch back, the residual carbon film on the LB film is removed by dissolving the LB film with methacrene. Methrene cannot dissolve SiO _{2 as} a mask substrate and a shifter material and Cr as a light shielding film material, so that only the carbon film and the LB film can be removed without damaging the light shielding body and the shifter. .

As the planarizing film having a two-layer structure, PI
Not only a combination of the BM LB film and the carbon film, but also a film that is soluble in a solution in which SiO ₂ and Cr are insoluble as a lower film and a film that can etch back a convex defect as an upper film. The lower layer film may be any film that can be mechanically removed with a brush or the like or a film that can be removed by a method that does not damage the SiO ₂ film and the Cr film.

In addition to the flattening film having the two-layer structure,
It is clear that at least the lowermost film may be a multi-layered planarization film composed of a film that is easily removed as described above.

(Example 14) In the fourteenth example, the FIB
A description will be given of how to prevent formation of a damage layer in an irradiation region and remove a protrusion of a convex defect and a flattening film.

When styrene or the like is used as the source gas for the flattening film, the film forming efficiency is low, and when a defect occurs, it takes a long time to repair the defect. In addition, since the film formation efficiency is low, the amount of ion irradiation during film formation is large, and after the simultaneous removal process, chemical dry etching is performed at a high temperature for a long time when removing the planarized film by chemical dry etching using O ₂ gas. Must be done.

When the projections of the convex defects and the flattening film are removed by sputter etching at the same etching rate, a damaged layer is formed in the FIB-irradiated region of the substrate. X to prevent the formation of this damaged layer
If assist etching using a gas containing eF ₂ or thermal etching using a laser beam is performed, extra digging is performed, and the margin of processing is reduced.

In order to solve the above problem, the present embodiment employs the following means.

First, when correcting a convex defect or a concave defect, the first and second thin films made of a material containing carbon are treated with methyl methacrylate gas, 2,4,4-trimethyl-
1- To be formed by FIB assisted deposition using pentene gas as a source gas.

As a result, the film formation efficiency of the flattening film can be improved, the time required for repair can be shortened, and the amount of ion irradiation at the time of film formation can be suppressed. The flattening film can be easily removed.

Second, when correcting a convex defect or a concave defect, the protrusion and the first and second thin films are simultaneously etched by FIB assisted etching using XeF ₂ gas and O ₂ gas or O ₃ gas. To be removed.

As a result, the etching rates of the flattening film and the shifter can be matched, and the correction can be performed without leaving any damage on the substrate surface. Therefore, the number of steps for removing the damaged layer can be reduced. Therefore, unnecessary digging that occurs during the damage layer removing step is eliminated.

Third, when correcting a convex defect or a concave defect, the first and second thin films remaining after the simultaneous removal step are treated with CF ₄ , H ₂ , H ₂ O, N ₂ , N ₂ O, Alternatively, removal is performed by chemical dry etching using a mixed gas obtained by adding at least one gas of NO to O ₂ gas.

Thus, when high-frequency power is applied,
Atomic oxygen to be discharged increases, and the removal rate of carbon increases. In addition, since carbon is removed from a low temperature, the throughput can be improved.

Next, a specific example of the present invention will be described.

Methyl methacrylate (monomer) which is liquid at normal temperature, (CH ₂ : C (CH ₃ ) COOCH ₃ ),
4,4-trimethyl-1-pentene ((CH ₃ ) ₃ CCH
₂ C (CH ₃ ): CH ₂ ), isoprene (CH ₂ : C (CH
₃ ) FIB assist deposition using CH: CH ₂ ) will be described with reference to FIG.

Methyl methacrylate, 2,4,4-trimethyl-1-pentene or isoprene was added to a gas cylinder 1
1, the inside of the gas cylinder 11 was evacuated, and a gas coming out was sprayed onto the sample 8 from the nozzle 13. At this time, the gas pressure in the nozzle 13 is 1 Torr. Next, a beam current of 10 pA, 25 keV G drawn out from the ion source 1 onto the sample to which gas is being sprayed.
The carbon film was formed on the sample 8 by irradiating aFIB.

When the film forming efficiency of the carbon film was examined in this way, when methyl methacrylate was used, 7.5 atom was used.
/ ion, which was 11 atom / ion when 2,4,4-trimethyl-1-pentene was used and 9 atom / ion when isoprene was used. In the specification of Japanese Patent Application No. 4-294536, it was described that simultaneous etching of the flattening film and the quartz substrate can be performed by FIB assisted etching using gas. At this time, the filament constituting the charge nutrizer may react with the gas used. For example, when a gas serving as an oxidizing agent is used, the tungsten filament reacts with the gas to form tungsten oxide, which adheres to the sample to be repaired and reduces the light transmittance. In order to prevent this, it is necessary to attach a cover to the tungsten filament, attach the generated tungsten oxide to the cover surface, and allow only electrons to reach the sample surface. Also, in order to suppress the generation of tungsten oxide and extend the life of the filament, it is desirable to perform differential evacuation to suppress the gas pressure near the filament.

In Japanese Patent Application No. 4-294536, a mixed gas containing XeF ₂ is used as a gas for simultaneous etching of the flattening film and the quartz substrate, so that the defect can be removed from the surface of the substrate. It can be done without. That is, although it depends on the film material of the flattening film to be used, when the flattening film is a carbon film formed by FIB assisted deposition, the etching rate of quartz is faster in a single atmosphere of XeF ₂ gas alone,
By adding a gas that functions as an oxidizing agent to the XeF ₂ gas, it is possible to make the etching rates of the flattening film and the shifter equal.

For example, a case will be described in which FIB assist deposition is performed using a mixed gas of XeF ₂ gas and O ₂ gas. FIG. 28 shows the etching rate when the O ₂ gas is added to the XeF ₂ gas having a gas partial pressure of 0.15 Torr, and the etching rates of carbon and quartz are matched when the O ₂ gas partial pressure is about 4 Torr or more. Become. FIG. 29 shows the change in the light transmittance at this time. As it can be seen from Figure 29, although the O ₂ partial pressure of the light transmittance decreases from the vicinity of 5 Torr, partial pressure of O ₂ indicates more than 93% even in the vicinity of 6 Torr. Actually, when an exposure experiment using a KrF excimer stepper was performed, even if the conditions such as the exposure amount, the depth of focus, and the development were changed, the transfer result was not affected.

By using the mixed gas of the XeF ₂ gas and the O ₂ gas as described above, the repair can be performed without leaving any damage on the substrate surface. Can be eliminated.

Here, since the allowable value of the difference between the etching rates of carbon and quartz varies depending on the use conditions of the mask, it is necessary to appropriately determine the allowable value depending on the use conditions of each mask.

For example, XeF _{2 with} a gas partial pressure of 0.15 Torr
When a gas is used, the range of the O ₂ gas partial pressure in which the difference between the etching rates of carbon and quartz falls within an allowable range is wide,
The etching yield is reduced to twice or less the sputtering yield, and the throughput is not significantly improved.

If it is desired to improve the throughput, use Xe
It is necessary to increase the pressure of F ₂ gas. For example, FIG. 30 shows a case where XeF ₂ gas having a gas partial pressure of 0.30 Torr is used.
Shown in In this case, when the curve indicating quartz and the curve indicating carbon intersect, the etching rates of the two coincide. The etching yield at this time is 7.3 times in the case of carbon and 5.6 times in the case of quartz, as compared with the case of sputtering, and improvement in throughput can be expected. FIG. 31 shows the change in the light transmittance at this time.
As can be seen from FIG. 31, the light transmittance is about 95%, and when an exposure experiment was actually performed using a KrF excimer stepper, transfer was performed even when the conditions such as the exposure amount, the depth of focus, and the development were changed. The results were not affected by the correction.

Also in this case, by using the mixed gas of the XeF ₂ gas and the O ₂ gas, the repair can be performed without leaving any damage on the substrate surface. Therefore, the step of removing the damaged layer can be reduced, and further excavation can be performed. It can be done without doing it.

Since the allowable value of the difference between the etching rates of carbon and quartz varies depending on the conditions of use of the mask, it is necessary to appropriately determine the allowable value according to the conditions of use of each mask.

In this case, since the range of the O ₂ gas partial pressure in which the difference between the etching rates of carbon and quartz falls within the allowable range is narrow, it is necessary to precisely control both the gas partial pressure and the total gas pressure. Such a feedback control mechanism is required.

In addition, as a gas functioning as an oxidizing agent, O
Even if using O ₃ gas as well as ₂ gas, no damage is left,
The etching rates of carbon and quartz can be matched. FIG. 32 shows a case where O ₃ gas + O ₂ gas is added to XeF ₂ gas having a gas partial pressure of 0.15 Torr. Usually, the concentration of O ₃ gas generated by an ozonizer is about 10% even for a high concentration. In the ozonizer used in this experiment, the O ₃ concentration at the outlet of the ozonizer was 10%. O ₃ gas + O ₂ gas is XeF ₂ at a gas partial pressure of 2.1 Torr.
When added to the gas, the etching rates of carbon and quartz are matched. FIG. 33 shows the change in the light transmittance at this time. As can be seen from FIG. 33, at this gas partial pressure, 95%
% Is shown. Further, when an exposure experiment was actually performed using a KrF excimer stepper, even if the conditions such as the exposure amount, the depth of focus, and the development were changed, the transfer result was not affected by the correction.

As described above, the XeF ₂ gas and the O ₃ gas + O ₂
By using a gas mixture of gases, the surface of the substrate is damaged.
Modifications can be made without leaving any changes. Therefore, it is possible to reduce the number of steps for removing the damage layer, and it is possible to eliminate the need for excavation. Here, the allowable value of the difference between the etching rates of carbon and quartz varies depending on the use conditions of the mask. Therefore, it is necessary to appropriately determine the allowable value depending on the use conditions of each mask.

In this case, since the range of the partial pressure of the O ₂ gas in which the difference between the etching rates of carbon and quartz falls within the allowable range is narrow, it is necessary to precisely control both the gas partial pressure and the total gas pressure. Such a feedback control mechanism is required.

When O ₃ is used as a gas that functions as an oxidizing agent, O ₃ is easily thermally decomposed even at a low temperature (it is instantly decomposed into O ₂ at 250 ° C. or higher). It is not possible to use a pressure gauge that contains a heat source inside. In the above example, a baratron is used, but it is necessary to use pressure measuring means that does not include a heat source inside.

In the specification of Japanese Patent Application No. 4-294536, carbon remaining in the periphery at the time of removing a convex defect is removed by CDE.
It can be removed with. As the gas used at this time, an O2 mixed gas can be used. In particular, CF ₄ ,
H ₂ O, N ₂ , N ₂ O, NO gas alone or in combination is added to O ₂ gas, high frequency power is applied, and discharged together to increase oxygen radicals, thereby increasing the carbon removal rate. It is possible to remove carbon from a lower temperature at a higher temperature, which is more effective.

For example, when H ₂ O is added to O ₂ gas,
Depends on the material of the carbon film, but O2 gas alone is 100 ° C
Although the etching starts near, the addition of H ₂ O starts the etching near room temperature. Although depending on the substrate temperature, the addition of H ₂ O at the same substrate temperature increases the etching rate by one digit. This H
The effect of improving the etching rate by adding ₂ O is only for carbon, and the etching rate is not improved for Cr or quartz, so that the addition of H ₂ O does not adversely affect the mask.

Further, the deposition of carbon, the simultaneous etching of carbon and SiO ₂ , and the removal of the damage layer are all performed by GaFIB, but are not limited to these ions. For example, it is clear that the processes in the above steps may be performed using other ions such as Au and Si.

(Example 15) In a fifteenth example, the use of a gas containing hydrogen atoms in molecules for removing a carbon film will be described.

In the first and second defect repairing methods, the carbon film can be removed by using hydrogen gas or a gas containing hydrogen atoms in molecules.

For example, a hydrogen gas flow rate of 20 sccm and a pressure of 0.
By applying 200 W of high frequency power at 5 Torr,
When the flattening film formed by FIB using pyrene as a source gas was removed using a parallel plate type RIE apparatus, only the flattening film could be removed without etching Cr and quartz. After removing the flattening film, no damage to the mask, such as a decrease in the light transmittance of the quartz substrate or reduction of the antireflection film on the surface of the light-shielding body, was observed, and the pattern using the corrected mask was not observed. No problems occurred in the transfer experiment.

In the above example, dry etching was performed using an RIE apparatus, but the dry etching method is not limited to this. The carbon film can be removed by an etching method using discharge of hydrogen gas or a gas containing hydrogen atoms in molecules, such as CDE, ECR etching, or magnetron RIE. Also, the removal method is not limited to dry etching, and hydrogen gas,
The carbon film can also be removed by laser light irradiation in a gas atmosphere containing hydrogen atoms in molecules.

The case where a carbon film formed by FIB using pyrene as a source gas is used as the flattening film has been described. However, styrene, methyl methacrylate,
Carbon film formed by FIB using a hydrocarbon gas such as 4,4-trimethyl-1-pentene, isoprene alone or a mixed gas of a hydrocarbon gas and hydrogen gas, or a film containing carbon such as a resist film It is also possible to apply to.

[0285]

As described above, according to the first and second defect repair processes, a film can be deposited flat on a convex defect, and the defect can be flattened by sputter etching by FIB or charged particle beam assisted etching. Can be processed. Damage to the quartz substrate can be removed by the charged particle beam assisted etching, and the remaining deposited film can be removed by an O ₂ asher or the like, whereby the convex defect can be corrected. Further, the concave defects can be filled by the charged particle beam assisted deposition, and the concave defects can be corrected flat by combining with the convex defect correcting process.
The film forming method of the present invention is suitable for forming a thin film in these defect correction processes.

That is, according to the present invention, there is provided a film forming method which can be used in a defect repairing process of a structure which can repair any of a convex defect or a concave defect to be flat in accordance with the substrate surface. You.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing an FIB apparatus used in a method according to an embodiment of the present invention.

FIG. 2 is a diagram showing a first half of a shifter convex defect repair process according to a first example.

FIG. 3 is a diagram showing the latter half of the shifter convex defect repair process according to the first example.

FIG. 4 is a view showing a measurement result of flatness by two-step film deposition.

FIG. 5 is a diagram showing the FIB acceleration voltage dependence of the etch rate ratio between the carbon film and SiO ₂ .

FIG. 6 is a graph showing the processing time dependency of the sputtering yield of a quartz substrate using GaFIB.

FIG. 7 is a diagram showing the processing time dependency of the etching yield of a quartz substrate by FIB assisted etching.

FIG. 8 is a cross-sectional view illustrating a process of repairing a shifter concave defect according to a second example.

FIG. 9 is a cross-sectional view for explaining a shape of embedding SiO _{2 in a} concave defect.

FIG. 10 is a cross-sectional view showing another example of embedding SiO ₂ into a concave defect.

FIG. 11 is a diagram showing the first half of a concave defect repair process in a shifter-edge portion of a shifter edge type phase shift mask according to a third example.

FIG. 12 is a diagram showing the latter half of the concave defect repair process at the shifter-edge portion of the shifter edge type phase shift mask according to the third example.

FIG. 13 is a view showing a process of correcting a convex defect at a shifter-edge portion of a shifter-edge type phase shift mask according to a fourth example.

FIG. 14 is a cross-sectional view showing a two-stage repair process of an irregular convex defect of a phase shifter according to a fifth example.

FIG. 15 is a cross-sectional view for explaining the problem of flattening irregular shaped convex defects.

FIG. 16 is a cross-sectional view showing a multi-stage repair process of an irregular convex defect of a phase shifter according to a fifth example.

FIG. 17 is a cross-sectional view showing a two-stage repair process of an irregular concave defect of a phase shifter according to a sixth example.

FIG. 18 is a cross-sectional view showing a multi-stage correction process of an irregular concave defect of a phase shifter according to a sixth example.

FIG. 19 is a view for explaining a seventh example, in which SiO _{2 is used.}
FIG. 4 is a characteristic diagram showing a change in transmittance before and after annealing of a film.

FIG. 20 is a sectional view showing a process of correcting a shifter concave defect according to an eighth example.

FIG. 21 is a cross-sectional view for explaining the shape of embedded SiO _{2 in a} concave defect.

FIG. 22 is a sectional view showing another example of embedding SiO ₂ into a concave defect.

FIG. 23 is a characteristic diagram showing Ga ⁺ ion energy dependence of the transmittance of a SiO ₂ deposited film with respect to light having a wavelength of 248 nm.

FIG. 24: Beam current density and Kr of deposited SiO ₂ film
7 is a graph showing a relationship between F light (wavelength: 248 nm) and light transmittance.

FIG. 25 is a graph showing the relationship between the ion energy and the O ₂ partial pressure ratio for each light transmittance with respect to KrF light (wavelength: 248 nm).

FIG. 26 is a diagram showing an atomic bonding state of TMCTS.

FIG. 27 is a schematic view showing an atomic bonding state of TMCTS and OMCTS.

FIG. 28 is a graph showing a relationship between an etching rate and a partial pressure of O ₂ .

FIG. 29 is a graph showing the relationship between light transmittance and O ₂ partial pressure.

FIG. 30 is a graph showing a relationship between an etching rate and an O ₂ partial pressure.

FIG. 31 is a graph showing the relationship between light transmittance and O ₂ partial pressure.

FIG. 32 is a graph showing a relationship between an etching rate and a partial pressure of O ₂ + O ₃ .

FIG. 33 is a graph showing a relationship between light transmittance and O ₂ + O ₃ partial pressure.

[Explanation of symbols]

101, 301: quartz substrate, 101: convex defect of phase shifter, 103: phase shifter pattern, 104, 207 ...
First deposited film, 105, 208... Second deposited film, 10
6, 205, 209, 306, 310: Focused ion beam, 107, 210, 311: Mass analyzer (secondary ion detector), 108, 211, 312: Damage layer, 20
1,302: phase shifter, 202: concave defect of phase shifter, 203, 304: nozzle, 204, 305: gas,
206, 307: protruding silicon oxide film, 303: concave defect formed at the edge of the phase shifter, 308: first
309 ... second carbon film, 313 ... excessive protrusion of silicon oxide film.

Continued on the front page (72) Inventor Mitsuyo Kariya 1 Toshiba, Komukai Toshiba-cho, Kawasaki-shi, Kanagawa Prefecture Inside the Toshiba R & D Center (72) Inventor Soichi Inoue 1 Toshiba-cho, Komukai Toshiba-ku, Kawasaki-shi, Kanagawa In the Toshiba R & D Center (72) Inventor Waka Sugihara 1st in Komukai Toshiba-cho, Yuki-ku, Kawasaki-shi, Kanagawa Prefecture In-Toshiba R & D Center (72) Inventor Ichiro Mori Small-sized Yuki-ku, Kawasaki-shi, Kanagawa No. 1 Muko Toshiba, Toshiba R & D Center (72) Inventor Keiji Horioka No. 1, Komukai Toshiba, Kochi, Kawasaki, Kanagawa Pref. Toshiba R & D Center (72) Inventor Motosuke Miyoshi, Kanagawa 72 Horikawa-cho, Sachi-ku, Kawasaki-shi Inside the Toshiba Horikawa-cho Plant (72) Inventor Toru Watanabe 1 Toshiba R & D Center, Komukai Toshiba-cho, Sachi-ku, Kawasaki-shi, Kanagawa Prefecture (72) Haruo Okano inventor 1 Kosaka Toshiba-cho, Saiyuki-ku, Kawasaki-shi, Kanagawa Toshiba Corporation In the R & D Center (72) Inventor Katsuya Okumura 1 Komagi Toshiba-cho, Saiwai-ku, Kawasaki City, Kanagawa Prefecture Inside the Toshiba Tamagawa Plant (72) Inventor Tadahiro Takigawa 1 Kochi Toshiba-cho, Koyuki-ku, Kawasaki City, Kanagawa Prefecture (72) Inventor Yuichiro Yamazaki 72 Horikawa-cho, Saiwai-ku, Kawasaki-shi, Kanagawa Prefecture F-term (reference) 2H095 BA01 BB03 BD38 4K030 AA01 AA06 AA09 AA14 BA44 FA12 LA11

Claims (8)

[Claims] 1. An FIB assist device for supplying a material having a Si—O—Si bond and a Si—H bond to a surface of a structure and irradiating a focused ion beam to a desired portion of the surface to which the material is supplied. A film forming method comprising a step of forming a silicon oxide film depending on a position. 2. Prior to the step of forming the silicon oxide film, at least one set value of energy of the focused ion beam, current density of the focused ion beam, and gas pressure at the time of FIB assist deposition is set. Determining the FIB assisted deposition with the energy of the focused ion beam, the current density of the focused ion beam,
The film forming method according to claim 1, wherein at least one of the gas pressures at the time of the FIB assist deposition is performed in accordance with the set value. 3. A material having a Si—O—Si bond and a Si—H bond and a gas containing an oxygen element-containing material are supplied to the surface of the structure, and the material is supplied to a desired portion of the surface to which the material is supplied. A film forming method comprising a step of forming a silicon oxide film by FIB assisted deposition for irradiating a focused ion beam. 4. Prior to the step of forming the silicon oxide film, the energy of the focused ion beam, the current density of the focused ion beam, the gas pressure at the time of FIB assist deposition, and the Determining at least one set value of the gas partial pressure at the time of performing the FIB-assisted deposition, the energy of the focused ion beam, the current density of the focused ion beam,
4. The film forming method according to claim 3, wherein at least one of a gas pressure during the FIB assist deposition and a gas partial pressure during the FIB assist deposition is performed in accordance with the set value. 5. The method according to claim 1, wherein the oxygen-containing material comprises O ₂ , O ₃ , and N.
5. The film forming method according to claim 1, wherein the material is selected from the group consisting of ₂ O. 6. The film according to claim 1, wherein the material having the Si—O—Si bond and the Si—H bond has a ring structure. Method. 7. The method according to claim 1, wherein the material having the Si—O—Si bond and the Si—H bond is 1,3,5,7-tetramethylcyclotetrasiloxane. 5. The film forming method according to any one of 4. 8. The film forming method according to claim 1, wherein a Ga beam or a Si beam is used as the focused ion beam.