JPH0558187B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a method for correcting missing defects in a photomask pattern, and particularly to a method for correcting missing photomask patterns that can obtain a repair film with excellent durability in a short period of time. be. [Background of the Invention] There are two types of photomask defects: residual defects and missing defects. These defects affect the yield of semiconductors such as LSI. Furthermore, since the correction of these defects greatly affects productivity, it is necessary to reduce the number of steps required for correction as much as possible and to carry out the correction in a short time. Of the above-mentioned defects that occur on photomasks, residual defects can be corrected using a laser
9508), a significant process reduction has been achieved. On the other hand, a lift-off method is used to correct missing defects, such as missing parts of normal patterns. This lift-off method is performed by the following steps. (1) Apply positive photoresist to the entire surface of the photomask that has missing defects. (2) Use the partial exposure method to expose only the missing defective parts. (3) Open a window in the resist at the missing defect area by developing. (4) Using vacuum evaporation technology, a metal film is formed on the resist in and around the missing defect, or on the entire surface of the photomask. (5) Remove the resist and at the same time remove the metal film formed on the resist. As described above, the lift-off method requires many steps and cannot be said to be sufficient for correcting missing defects in photomasks in terms of production, posing a major technical problem. Furthermore, recently, a method has been reported in which a metal is deposited from an organometallic solution by laser beam irradiation. (Yokoyama et al.: Metal Deposition from Organometallic Solutions by Laser Light Irradiation: Spring 1981 30th Applied Physics Association Lecture Proceedings P.202) As shown in Figure 3, this is a Cr complex or Mo A benzene complex solution 1 is put into a cell 3 having two glass windows 2, and a laser beam 4 is focused inside one of the glass windows 2a by an objective lens 5 to deposit a metal 6. The inventors attempted to apply this technique to the correction of missing defects in photomasks. However, the Cr complex or Mo complex used here is extremely unstable, and when exposed to the atmosphere, it reacts with oxygen in the atmosphere to form an oxide, making it difficult to handle and the metal deposited. However, there are technical problems in directly applying this technology to correcting missing defects in photomasks. By the way, before a photomask is used for exposing a wafer or the like, it is subjected to scrub cleaning using a nylon brush or the like or chemical cleaning using hot concentrated sulfuric acid or the like. Therefore, the portion of the photomask in which missing defects have been corrected is required to have excellent abrasion resistance and chemical resistance so that it can withstand such cleaning during use. In this respect, the lift-off method described above can be modified to have excellent chemical resistance by appropriately selecting the metal to be deposited. However, regarding abrasion resistance, even if the deposited metal film itself has excellent abrasion resistance, photoresist residue due to variations in exposure and development conditions, and exposure from development to vacuum deposition may cause Contaminants due to adsorption of moisture and the like may adhere to the defective parts, reducing the adhesion to the substrate and causing peeling during scrubbing. On the other hand, in the method using an organic metal solution, the deposited metal tends to be in a state of agglomeration of particles, so there is a problem in wear resistance. [Object of the Invention] The present invention solves the above-mentioned conventional problems, corrects missing defects in mask patterns in a shorter time using a simpler process than the conventional method, and provides wear resistance comparable to that of the conventional lift-off method. An object of the present invention is to provide a method for repairing missing defects in a photomask having excellent durability and chemical resistance. [Summary of the Invention] In order to achieve the above object, the present invention oxidizes and oxidizes contaminants attached to the missing defects in a vacuum container in which a photomask having missing defects is installed.
After a cleaning process to decompose, bis-benzene-chromium, bis-benzene-chromium, and
A CVD material gas selected from molybdenum, chromium carbonyl, and tungsten carbonyl is introduced, and a laser beam matched to the position and size of the missing defect is irradiated to the missing defect to convert the CVD material gas into the CVD material gas. This photomask defect repair method is characterized in that the missing defect portion is repaired by forming a light-shielding film by depositing a corresponding metal. Further, the present invention is characterized in that the cleaning treatment in the photomask defect repair method is performed by irradiating ultraviolet light to the missing defective portion of the photomask while the inside of the container is in an ozone atmosphere. [Embodiment of the Invention] Hereinafter, a description will be given of FIG. 1 showing an embodiment of the present invention. In the figure, reference numeral 8 denotes a repair container which holds a photomask having a missing defect in its upper part with its pattern surface 7' facing downward, and holds a window 16 in its lower part. Further, the correction container 8 connects the photomask 7 and the window 16 inside thereof to a vacuum pump 13 via a valve 12,
It is connected to an inert gas cylinder 15 through a valve 14, an ozone generation chamber 34 through a valve 27, an oxygen gas cylinder 28 through this ozone generation chamber 34 and a valve 33, and a vacuum gauge 2.
Connected to 9. The ozone generation chamber 34 is formed of an insulator such as a quartz glass tube, and has two electrodes 3.
5, 36 are inserted. One of the electrodes 35
is connected to a high frequency power source (not shown) in the control device 26, the other electrode 36 is connected to ground 36',
These two electrodes 35 and 36 are supplied into the ozone generation chamber 34 from the oxygen gas cylinder 28 when a high frequency electric field is applied from the high frequency power supply.
It is like converting O ₂ to O or O ₃ . 11
is a sealed correction substance container whose inside is filled with vacuum or inert gas, with a correction substance 10 such as bis-benzene-chromium or bis-benzene-molybdenum held in the upper part, and a correction substance 10 such as bis-benzene-chromium or bis-benzene-molybdenum held in the lower part. A heater 17 is provided to heat and vaporize the correction substance 10. Reference numeral 18 denotes a laser irradiation optical system, in which a laser beam 20 oscillated from a laser oscillator 19a is reflected by a dichroic mirror 21 tilted at an angle of 45° via a shutter 19b, and then an objective lens 22 is used to detect the missing part of the photomask. It is formed so as to focus and irradiate the defective part. Reference numeral 23 designates an observation optical system, which directs illumination light from an illumination light source 23a through a lens 23b, a half mirror 24 tilted at an angle of 45°, the dichroic mirror 21, and the objective lens 22, to the missing defective portion of the photomask 7. The laser beam is irradiated, and the ocular lens 25 is used to observe the missing defective portion of the photomask 7 and the irradiation position relationship between the laser beam and the missing defective portion through the objective lens 22, the dichroic mirror 21, and the half mirror 24. . Reference numeral 30 denotes an ultraviolet light lamp, which emits ultraviolet light 32 having a strong emission spectrum of, for example, 200 to 300 nm. 31 is an elliptical mirror, and the ultraviolet light lamp 30
The ultraviolet light 32 is focused and irradiated onto the defective portion of the photomask 7, and the O ₃ in the repair container 8 is decomposed by the ultraviolet light 32 and converted into O + O ₂ .
The contaminants (not shown) adhering to the missing defective portions of the photomask 7 are oxidized and decomposed, and the chemical bonds of the contaminants are broken by the ultraviolet light 32, and then discharged to the outside of the container 8 by the vacuum pump 13. do.
26 is a control device, and the five valves 9, 12,
Opening and closing of 14, 27, 33, two electrodes 35, 36
Application of a high frequency electric field to the shutter 19b, opening/closing of the shutter 19b, and ON/OFF of the ultraviolet light lamp 30 are automatically controlled. With the above configuration, the photomask 7 is held at the top of the correction container 8 with all valves 9, 12, 14, 27, and 33 closed, and then the valve 12 is opened and the vacuum pump 13 is activated to make corrections. Gas such as air inside the container 8 is discharged.
In addition, the heater 17 is activated, and the correction material 1 above it is activated.
0 to evaporate the correction material 10. Heating by this heater 17 may be performed all the time,
100 if the modifier is bis-benzene-chromium
Sublimation occurs at ~290℃, and in the case of bis-benzene-molybdenum at 50-100℃. Thereafter, while observing the missing defective part of the photomask 7 using the illumination light source 23a, half mirror 24, eyepiece lens 25, and objective lens 22, the focal point of the laser beam 20 is aligned with the missing defective part. Next, the pressure inside the correction container 8 is measured using the vacuum gauge 29, and when the pressure reaches a predetermined pressure value (for example, 1×10 ^-3 torr) or less, the valves 27 and 33 are opened to supply O ₂ from the oxygen gas cylinder 28. is supplied into the ozone generation chamber 34 and converted into O+O or O ₃ +O by a high frequency electric field applied to the two electrodes 35 and 36, and introduced into the correction container 8. Thereafter, the ultraviolet light lamp 30 is turned on, and the ultraviolet light 32 is focused and irradiated onto the defective portion of the photomask 7 through the elliptical mirror 31. Then, O ₃ is decomposed into O + O ₂ in the correction container 8 which is in the optical path of the ultraviolet light 32, and
The chemical bonds of contaminants adhering to the defective portions of the photomask 7 are broken by irradiation with the ultraviolet light 32. Contaminants that have not been decomposed by the ultraviolet light 32 are oxidized by strong oxidizing agents such as O ₃ and O to produce H ₂ O, CO _2, etc., which are then pumped into the correction container 8 by the vacuum pump 13. Excrete from within. After that, after a certain period of time has passed, the valves 27, 33
closes, the application of the high frequency electric field to the two electrodes 35 and 36 is stopped, and the ultraviolet light lamp 30 is turned off.
It turns off. As a result of the above, the missing defective portion of the photomask 7 is in a clean and chemically activated state. When the vacuum pump 13 is driven for a certain period of time and the contaminants etc. in the correction container 8 are completely discharged,
Valve 12 is closed and valve 14 is opened to supply inert gas into the correction container 8. After that, the above correction container 8
When the inside is filled with inert gas to about atmospheric pressure, valve 1
4 is closed, the valve 12 is opened again, and the inert gas and remaining trace amounts of O, O ₂ and
Drain _O3 . When the pressure inside the correction container 8 reaches a predetermined pressure (for example, 1×10 ⁻⁵ torr) or less, the valve 12
is closed, and the valve 9 is opened to supply the vapor of the correction substance 10 in the correction substance container 11 into the correction container 8 until a constant pressure (for example, 1×10 ⁻² torr) is reached.
Next, the valve 9 is closed, the shutter 19b is opened, and the laser beam 20 from the laser oscillator 19a is focused and irradiated onto the missing defect part of the photomask 7. If the missing defect area is larger than the spot diameter of the laser beam 20, , correction container 8 and laser irradiation optical system 1
8. By moving the observation optical system 23 or by inserting two wedge-shaped prisms into the optical path of the laser beam 20 and rotating them in opposite directions, or by tilting the dichroic mirror 21, the laser beam 20 is
0 is focused and irradiated while scanning the missing defective part of the photomask 7, and when a certain period of time has elapsed or scanning of a certain area is completed, the shutter 1
Close 9b. In this way, when the defective part of the photomask 7 is heated by condensing and irradiating the laser beam 20, the correction material 10 (more than 300°C in the case of bis-benzene-chromium, more than 300°C in the case of bis-benzene-molybdenum) (110℃ or higher) decomposes and chromium or molybdenum precipitates, forming a light-shielding film at the missing defect. Then, after opening the valve 12 to discharge the vapor of the correction substance 10 in the correction container 8, the valve 1 is opened.
2 is closed, the valve 14 is opened, and inert gas is supplied from the inert gas cylinder 15 into the correction container 8 to make the pressure in the correction container 8 substantially equal to atmospheric pressure. At this time, it is also possible to supply inert gas into the correction container 8 for a certain period of time and discharge it, then close the valve 12 and continue to fill the correction container 8 with inert gas to a pressure approximately equal to atmospheric pressure. do not have. Incidentally, by opening the valves 9 and 12, the above-mentioned correction substance 10 is transferred to the correction container 8.
Laser irradiation may also be performed while flowing the liquid inside. At this time, a flow controller or the like is required to keep the pressure inside the correction container 8 constant. Then, with all valves 9, 12, 14, 27, and 33 closed,
When the photomask 7 is removed, the correction of the missing defective portion of the photomask 7 is completed. Note that in the above embodiment, the laser irradiation optical system 18 and the observation optical system 23
Although the ultraviolet light lamp 30 and the elliptical mirror 31 are positioned below and the ultraviolet light lamp 30 is positioned above, the present invention is not limited to this, and they may be positioned in the opposite direction. Next, FIG. 2 is an explanatory diagram of a laser irradiation optical system and an observation optical system showing another embodiment of the present invention. Components having the same configuration as in FIG. 1 are designated by the same reference numerals as in FIG. 1. As shown in the figure, a laser beam 20 oscillated from a laser oscillator 19a has its beam diameter expanded by a beam expander 40, and is connected to a reference light source 41, a reference beam 43 of a specific wavelength by an interference filter 42, and a coupling optical system 44. The light beams are coupled to the same optical axis and irradiated onto the rectangular aperture slit 45. With the shutter 19b closed, the operator
1. While observing the photomask 7 attached to the correction container 8 through the half mirror 46, the illumination optical system 37, the laser beam cut filter 38, the prism 39, and the eyepiece 25, the image of the rectangular opening slit 45 by the reference beam 43 is captured. , adapted to the missing defect location and size. At this time, the rectangular aperture slit 45, the objective lens 22, and the photomask 7 are arranged in a positional relationship such that the image of the rectangular aperture slit 45 is formed on the photomask 7 at a size of 1/M, assuming that the magnification of the objective lens 22 is M. has been done. In this state, by opening the shutter 19b for a certain period of time, a rectangular opening slit 4 is formed by the reference beam 43 that is adjusted to the size and position of the missing defect.
20 laser beams at exactly the same size and position as the 5 images
is irradiated. Here, the reference light 43 is the laser light 2
0 wavelength and no chromatic aberration due to the objective lens 22,
The interference filters 42 select different values to the extent that they can be combined by the combining optical system 44. In addition, the dichroic mirror 21 has a sufficiently high reflectance for the wavelength of the laser beam 20, a reflectance of about 50% for the reference beam 43, and a sufficiently high reflectance for other wavelengths. It is desirable to have a transmittance. Alternatively, if the laser beam 20 is linearly polarized, a polarizing beam splitter is used as the coupling optical system 44, and the laser beam 20 and the reference beam 43 after being coupled have exactly the same wavelength and are used with only the polarization directions perpendicular to each other. You can also. In this case, the dichroic mirror 21 is one that reflects light in the polarization direction of the laser beam 20 sufficiently highly and has a reflectance of nearly 50% for the polarization component orthogonal to it.
As a laser beam cut filter 38, the laser beam 2
By using a material that reflects or absorbs light in the zero polarization direction, correction can be performed while completely ignoring the chromatic aberration between the laser beam 20 and the reference beam 43. Note that the arrangement of the above optical system and the ultraviolet light irradiation optical system may be reversed in the vertical direction as in the above embodiment. In the optical system described above, the laser beam 20
Because the optical system shown in Figure 1 uses a laser beam 20 with a Gaussian distribution to extract and irradiate a portion where the power distribution is approximately uniform, it is also possible to irradiate a wide area at once. A good deposited film can be obtained. Note that the laser oscillator 19
If the oscillation wavelength of a is in the ultraviolet region of 200 to 300 nm, the ultraviolet light irradiation device and control device 26 in FIG.
The ON/OFF control unit for the ultraviolet light lamp 30 becomes unnecessary. In this case, the cleaning procedure for the cleaning part of the missing defective part is the same as the procedure shown in FIG. be. We also mentioned bis-benzene-chromium and bis-benzene-molybdenum as correction substances;
The material is not limited to this, and for example, chromium carbonyl, tungsten carbonyl, or the like may be used. As the inert gas, one that does not react with the correction substance is used, such as N ₂ , He, Ar, etc. The laser light source (oscillator 19a) may also be of any type as long as it can pass through the photomax substrate or window material 16, and may include fundamental waves and harmonics of Ar laser or YAG laser, Kr laser,
Dye lasers with various excitation methods can be used. Furthermore, the correction container 8 may be provided with electrodes 35 and 36, and the correction container 8 itself may be used as an ozone generation chamber. In that case, as a matter of course, either the ozone generation chamber 34 or the valves 27 and 33 becomes unnecessary. Note that if metal is precipitated beyond the missing defect by the repair according to the present invention, it can be repaired by repairing the remaining defect using a conventional laser. [Effects of the Invention] As detailed above, according to the photomask defect repair method according to the present invention, vapor phase growth method (laser
Chemically stable metals (Cr, Mo,
Since the light-shielding film W) is formed, it is possible to form a light-shielding film with excellent wear resistance and chemical resistance on the missing defective portion of the photomask. Furthermore, since the cleaning treatment of the missing defective portion is carried out in one container without exposing it to the atmosphere, it is possible to obtain a light-shielding film with excellent adhesion. Furthermore, since the cleaning process and the formation of the light-shielding film are performed continuously in one container, the only step required for correction is to align the focal point of the laser beam with the missing defect. By significantly reducing the number of processes, the time required for corrections can be significantly reduced and productivity can be greatly improved. Since the light-shielding film is obtained by vapor phase growth in a vacuum, missing defects can be corrected with high accuracy, and the yield of products can be greatly improved.

[Brief explanation of drawings]

Fig. 1 is an explanatory diagram of a photomask missing defect correction device showing one embodiment of the present invention, Fig. 2 is an explanatory diagram of an optical system showing another embodiment of the invention, and Fig. 3 is a conventional photomask. FIG. 2 is an explanatory diagram of a missing defect correction device. 1... Benzene solution, 2... Glass window, 3...
Cell, 4... Laser light, 5, 22... Objective lens, 6... Metal, 7... Photomask, 8... Correction container, 9, 12, 14, 27, 33... Valve, 1
0... Correction substance, 11... Correction substance container, 13...
...Vacuum pump, 15...Inert gas cylinder, 16
... Window, 17 ... Heater, 18 ... Laser irradiation optical system, 19a ... Laser oscillator, 19b ... Shutter, 20 ... Laser light, 21 ... Dichroic mirror, 23 ... Observation optical system, 24, 46...
Half mirror, 25... Eyepiece, 26... Control device, 28... Oxygen gas cylinder, 29... Vacuum gauge, 30... Ultraviolet light lamp, 31... Elliptical mirror, 32... Ultraviolet light, 34... Ozone generation room, 3
5, 36... Electrode, 37... Illumination optical system, 38...
...laser light cut filter, 39...prism,
40...Beam expander, 41...Reference light source, 42...Interference filter, 43...Reference light, 4
4...Coupling optical system, 45...Slit.

Claims (1)

[Scope of Claims] 1. After performing a cleaning process to oxidize and decompose contaminants adhering to the missing defective parts in a vacuum container in which a photomask having missing defective parts is installed, screws are placed in the vacuum container.・Benzene ・Chromium, Bis・
CVD selected from benzene molybdenum, chromium carbonyl, tungsten carbonyl
A material gas is introduced, and a laser beam matched to the position and size of the missing defect is irradiated to the missing defect to deposit a metal corresponding to the CVD material gas, thereby forming a light-shielding film. A photomask defect repair method characterized by repairing a missing defect portion. 2. The photomask defect repair method according to claim 1, wherein the cleaning treatment is performed by irradiating the missing defective portion of the photomask with ultraviolet light while creating an ozone atmosphere in the container.