JP2013129565A - Method for restoring flaw of surface of substrate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for locally restoring minute flaws of the surface of a substrate in a short time.SOLUTION: The method includes supplying a precursor to the periphery of minute flaws of the surface of the substrate, and irradiating the precursor with first laser beams causing the decomposition reaction of the precursor and irradiating the flaws with second laser beams causing the temperature rise of the substrate each simultaneously, so that the minute flaws of the surface of the substrate are restored locally in a short time.

Description

  The present invention relates to a method for locally repairing minute scratches on a substrate surface in a short time.

  Fine scratches on the surface of a substrate used in the semiconductor and liquid crystal fields often cause problems because they cause light scattering and a decrease in transmittance. Heretofore, several methods for removing or repairing such fine scratches have been proposed. A generally known method is to remove the scratches by polishing the surface of the substrate more than the depth of the scratches by chemical mechanical polishing. However, this method has a problem that it takes a very long time per substrate to remove the scratches, resulting in a lack of productivity.

  Therefore, Patent Document 1 proposes a method of repairing a scratch by applying a planarizing material having a refractive index equal to that of the glass substrate to the damaged glass substrate. However, in this method, it is necessary to apply a planarizing material even to a portion having no scratch, and there is a lot of waste of raw materials. Further, when the substrate is large, it is extremely difficult to uniformly apply the entire surface.

JP 10-333132 A

  An object of the present invention is to provide a method for locally repairing fine scratches on a substrate surface in a short time.

  In the repair of fine scratches on the surface of the substrate, the present inventors supply a precursor to the periphery of the scratch and cause the first laser to cause a decomposition reaction of the precursor to the precursor to increase the temperature of the substrate with respect to the scratch. By simultaneously irradiating each of the second lasers that cause the damage, it was found that the scratched portion was filled with the precursor reactant, and the scratch could be repaired locally in a short time, thereby completing the present invention. .

  Hereinafter, the present invention will be described in detail.

  In the present invention, a precursor is supplied to a wound peripheral portion of a substrate surface, and a first laser that causes a precursor decomposition reaction to the precursor is simultaneously irradiated with a second laser that causes a temperature increase of the substrate to the scratch. The present invention relates to a method for repairing fine scratches on a substrate surface.

  First, a method for supplying the precursor to the wound peripheral portion of the substrate surface will be described.

  The substrate used in the present invention is preferably a substrate that cannot be used for a specific purpose if there are fine scratches on the surface of a quartz glass substrate or Si wafer.

  The precursor used in the present invention is not particularly limited as long as it can repair scratches, but in view of ease of handling, a compound having a metal-oxygen bond is preferable. As the compound having a metal-oxygen bond, for example, a compound having a Si—O bond, a Ti—O bond, or a Zr—O bond can be used. Examples of the compound having a Si—O bond include silicone oil, silicon alkoxide such as tetraethoxysilane, and cyclic siloxane such as octamethylcyclotetrasiloxane.

  Among these precursors, a precursor that is liquid at room temperature is vaporized by heat in advance.

  The method for supplying the precursor is not particularly limited, and for example, there is a method for supplying using a carrier gas.

  Next, a method of simultaneously irradiating the first laser that causes the precursor decomposition reaction to the precursor and the second laser that causes the substrate temperature to rise to the scratch will be described with reference to the drawings.

  The first laser (4 in FIG. 1) used in the present invention is applied to the precursor (3 in FIG. 1), and the effect thereof causes the precursor to be decomposed.

  The laser type of the first laser is not particularly limited as long as it causes a precursor decomposition reaction, and an ultraviolet laser having a wavelength of 150 to 380 nm, which is known to cause the precursor photolysis, is preferably used.

  The light diameter of the first laser is not particularly limited.

  The irradiation direction of the first laser is preferably parallel to the substrate in that the first laser does not cause photoexcitation or temperature rise of the substrate.

  The optical path of the first laser preferably passes directly above the scratch in that the material decomposed by the first laser is immediately supplied to the scratch. However, if the optical path is too close to the substrate, there is a possibility that the temperature of the substrate may increase due to convection of the atmospheric gas heated by light absorption or radiation.

  The second laser (5 in FIG. 1) used in the present invention is applied to the wound (2 in FIG. 1), and the effect thereof is that the temperature of the wound is increased locally and rapidly. The substance decomposed by the laser is solid-formed only at the scratched part at high speed.

  The laser type of the second laser is not particularly limited as long as it causes the temperature of the substrate to rise, and an infrared laser having a wavelength of 800 to 11000 nm is preferable. Among these, a pulsed laser or a continuous wave laser is intermittently a laser. What was processed so that light may be irradiated is still more preferable. As described above, the second laser has a role of heating the flaw. If this heating is performed continuously, the periphery of the scratches is also heated by heat conduction, and local solid formation becomes difficult. For this reason, it is preferable to repeat instantaneous heating and heat dissipation by a laser that oscillates intermittently so that the periphery of the wound is not heated.

  The light diameter of the second laser is not particularly limited, but is adjusted by an optical device (6 in FIG. 1) so that the light diameter is approximately the same as the size of the scratched part in that only the scratched part is irradiated with the second laser. And irradiation is preferable.

  By simultaneously irradiating the first laser and the second laser, the flaw is filled with the reactant of the raw material precursor, and the flaw can be repaired locally in a short time.

  The temperature of the quartz glass substrate at the time of laser irradiation needs to be higher than the temperature at which condensation of the precursor occurs. However, care should be taken because if the substrate temperature is too high, solids may be formed in the periphery of the scratches.

  The pressure at the time of laser irradiation is not particularly limited, and can be performed under atmospheric pressure.

  The laser irradiation time varies depending on the depth of the scratch and may be irradiated until the scratch is filled with the forming material.

  In the scratch repairing method of the present invention, the etching process can also be performed after laser irradiation. This effect is to remove the original scratches while maintaining the smoothness of the surface by etching the thickness beyond the depth of the scratches after repairing the scratches.

  The etching method is not particularly limited, and may be dry etching or wet etching.

  When the substrate is quartz glass, tetrafluoromethane is widely used for dry etching and hydrofluoric acid is widely used for wet etching.

  This etching process is particularly useful when a scratch is repaired by a precursor containing atoms other than the substance constituting the substrate. For example, when a scratch is repaired with a precursor as described above on a quartz glass substrate, there is a possibility that an optical abnormality occurs in the repaired portion because the refractive index of the repaired portion and the quartz glass substrate are different. Therefore, the repaired portion and the quartz glass substrate are etched to a thickness greater than the depth of the scratch under the etching conditions that make the respective etching rates substantially equal, and the repaired portion and the original scratched portion are maintained while maintaining the smoothness of the surface. Remove.

For example, if a compound having a Ti—O bond is used for the precursor, TiO ₂ is formed at the scratch. TiO ₂ is not etched with hydrofluoric acid. As a wet etching solution of TiO ₂ , for example, there is a mixed solution of ammonium carbonate and hydrogen peroxide (see Japanese Patent Application Laid-Open No. 2004-71585). Quartz glass is not etched with the mixed solution. Therefore, the TiO ₂ and the quartz glass substrate are etched at the same rate by a mixed solution in which hydrofluoric acid, ammonium carbonate, and hydrogen peroxide are mixed at an appropriate concentration, and the original scratches are maintained while maintaining the smoothness of the surface. Part can be removed.

  According to the present invention, it is possible to locally repair minute scratches on the substrate surface in a short time.

It is the schematic which shows an example of the irradiation method of the 1st laser and 2nd laser which concern on this invention.

  EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to such examples.

  The film thickness was measured by a monochromatic ellipsometry method.

Example 1
A siliceous film was obtained using octamethylcyclotetrasiloxane as a precursor and a Si wafer (20 mm × 20 mm × 0.73 mm) as a base in the following manner.

  First, octamethylcyclotetrasiloxane was heated to 70 ° C. and vaporized, and this was supplied to a Si wafer heated to 75 ° C. using air as a carrier gas. Here, a YAG laser (wavelength: 1064 nm) was irradiated on the Si wafer from above the Si wafer, and an ArF laser (wavelength: 193 nm) was irradiated at an atmospheric pressure 5 mm above the Si wafer in parallel to the Si wafer. The irradiation time at that time was a time when the central film thickness of the film formed in the laser irradiation region was 900 nm. As a result, a film was formed in the laser irradiation region, but no film was formed outside 1 mm from the laser irradiation region.

Comparative Example 1
A siliceous film was obtained using octamethylcyclotetrasiloxane as a precursor and a Si wafer (20 mm × 20 mm × 0.73 mm) as a base in the following manner.

  First, octamethylcyclotetrasiloxane was heated to 70 ° C. and vaporized, and this was supplied to a Si wafer heated to 300 ° C. using air as a carrier gas. Here, an ArF laser (wavelength: 193 nm) was irradiated onto the Si wafer from above the Si wafer. The irradiation time at that time was a time when the central film thickness of the film formed in the laser irradiation region was 900 nm. As a result, a film was formed on the substrate, and the film thickness of the film 1 mm outside the laser irradiation region was 450 nm.

  Fine scratches on the substrate surface can be repaired locally in a short time, and the production yield can be improved.

1: Substrate 2: Fine scratches on the substrate surface 3: Precursor 4: First laser 5: Second laser 6: Condensing lens

Claims (6)

  A precursor is supplied to the periphery of a fine flaw on the substrate surface, and a first laser that causes a precursor decomposition reaction to the precursor and a second laser that causes a temperature rise of the substrate to the flaw are simultaneously irradiated. Thus, the method for repairing fine scratches on the surface of the substrate, wherein the scratches are filled with the precursor reactant.   2. The method for repairing fine scratches on a substrate surface according to claim 1, wherein the substrate is a quartz glass substrate.   3. The method for repairing fine scratches on a substrate surface according to claim 1 or 2, wherein the first laser is an ultraviolet laser having a wavelength of 150 to 380 nm, and the second laser is an infrared laser having a wavelength of 800 to 11000 nm.   The method for repairing fine scratches on a substrate surface according to any one of claims 1 to 3, wherein the precursor has a metal-oxygen bond.   The method for repairing fine scratches on a substrate surface according to any one of claims 1 to 4, wherein the precursor has a siloxane (Si-O) bond.   6. A step of etching a thickness greater than the depth of the scratch under an etching condition in which the etching rate of the quartz glass substrate is substantially equal to the material formed in the scratch after irradiation of the first laser and the second laser. A method for repairing fine scratches on a substrate surface according to any one of the above.

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