JP6357319B2 - Method and apparatus for cleaning substrate to be cleaned - Google Patents

Description

  The present invention relates to a cleaning method for cleaning a substrate to be cleaned, in which a substrate to be cleaned is held on a table and cleaned with a cleaning liquid in a step of cleaning a precision substrate used for manufacturing a semiconductor device such as a silicon wafer or a glass substrate. And a substrate cleaning apparatus.

  In a manufacturing process of a semiconductor device, a liquid crystal display (LCD), etc., photolithography is performed using a mask substrate on which a desired pattern is formed in order to form a fine pattern on a silicon wafer, a glass substrate, or the like. If foreign matter such as particles adheres to the mask substrate in this photolithography process, it causes a pattern formation failure. In addition, if a foreign substance adheres to a semiconductor substrate during device manufacture, it causes a defect and deteriorates the yield of device manufacture. Therefore, there is a big problem of how to remove and remove the foreign matter adhering to the semiconductor substrate, the photomask substrate and the like.

  In a cleaning apparatus for silicon wafers, photomask substrates, glass substrates, and III-V semiconductor substrates, a mixed solution of sulfuric acid and hydrogen peroxide solution, a mixed solution of ammonia and hydrogen peroxide, a potassium hydroxide solution, A method is used in which an organic substance present on the surface of a substrate to be cleaned is removed using a sodium hydroxide solution or an organic solvent as a cleaning liquid. The process of removing organic substances in the cleaning for fine foreign substances is an important process for removing foreign substances present in the organic substances.

JP 2008-311256 A

  When using the solution shown above, it is necessary to use the cleaning solution at a high temperature in order to obtain a high cleaning effect. Therefore, in each part of the cleaning apparatus such as a cleaning liquid supply mechanism for supplying the cleaning liquid, it is necessary to select a material with higher durability, and there is a problem that the operation cost is high. At the same time, there is also a problem that a large amount of load and cost are required for disposal of such a solution after the cleaning process is completed.

  For such a problem, there is a cleaning method using ozone water as a cleaning liquid (see Patent Document 1). Patent Document 1 describes a cleaning method in which ozone water is irradiated with ultraviolet rays to photolyze a part of ozone to generate OH radicals, and the photoresist is decomposed and removed by the OH radicals.

  However, in order to remove organic substances on the substrate to be cleaned more effectively, there is a problem that it is necessary to generate OH radicals in the cleaning liquid with higher efficiency and supply the substrate to the substrate to be cleaned.

  The present invention has been made in view of the above-described problems, and an object thereof is to provide a cleaning method and a cleaning apparatus that are low in operational cost, can generate OH radicals with high efficiency, and have a high cleaning effect. .

  In order to achieve the above object, according to the present invention, there is provided a cleaning method for cleaning a substrate to be cleaned by holding the substrate to be cleaned and supplying a cleaning liquid from a discharge port of a cleaning liquid supply mechanism onto the substrate to be cleaned. In the cleaning liquid supply mechanism, a pipe resistance is added to the cleaning liquid, and a light source that emits ultraviolet light is brought into contact with the cleaning liquid, and the ultraviolet light is irradiated while heating the cleaning liquid. The present invention provides a method for cleaning a substrate to be cleaned, which generates active OH radicals and supplies the cleaning liquid containing the OH radicals from the discharge port to clean the substrate to be cleaned.

  In this way, the generation of OH radicals is promoted in the cleaning liquid more efficiently than in the past by continuously adding decomposition factors such as physical impact due to pipe resistance, heat from the light source, and ultraviolet rays from the light source to the cleaning liquid. Sufficient OH radicals can be generated. Therefore, the cleaning effect can be enhanced as compared with the conventional case. Further, since it is not always necessary to use a high-temperature strong acid, strong base, or the like, washing can be performed with low load and low cost.

At this time, the cleaning liquid may be ultrapure water, inorganic acid, inorganic alkali, organic acid, organic alkali, ozone water, electrolytic water, or a cleaning liquid in which two or more of these are mixed.
In the cleaning method of the present invention, in particular, by using these solutions as cleaning liquids, OH radicals can be reliably generated in the cleaning liquid, and the substrate to be cleaned can be effectively cleaned. The cleaning liquid of the present invention is preferably a solution that promotes the generation of OH radicals.

At this time, the ultraviolet light is preferably ultraviolet light having a wavelength of 200 nm to 400 nm.
In this way, sufficient OH radicals can be generated more efficiently, and the cleaning effect can be improved more reliably.

At this time, it is preferable that the distance between the discharge port and the substrate to be cleaned is within 5 mm.
In this way, the cleaning liquid can be supplied to the substrate to be cleaned before the generated OH radicals self-extinguish, and the substrate to be cleaned can be reliably cleaned with a higher cleaning effect.

At this time, the substrate to be cleaned can be any of a photomask substrate, a glass substrate, a Si wafer, a Ge wafer, a GaAs wafer, a SiC wafer, a flat panel, and a substrate used in a manufacturing process of a multilayer ceramic.
The cleaning method of the present invention can perform effective cleaning when cleaning a precision substrate related to the manufacture of such semiconductor devices.

  In order to achieve the above object, according to the present invention, a table for holding a substrate to be cleaned, a cleaning liquid supply for introducing the cleaning liquid from the introduction port, and supplying the introduced cleaning liquid to the substrate to be cleaned from the discharge port A cleaning apparatus for cleaning the substrate to be cleaned with the cleaning liquid, wherein the cleaning liquid supply mechanism includes a rectifying means for adding piping resistance to the cleaning liquid introduced from the introduction port, and the cleaning liquid The cleaning solution is heated to irradiate the cleaning solution with ultraviolet light, and the rectifying means and the light source generate active OH radicals in the cleaning solution and contain the OH radicals. There is provided a cleaning apparatus for a substrate to be cleaned, wherein the substrate to be cleaned is cleaned by supplying the cleaning liquid from the discharge port.

  In this way, the generation of OH radicals is promoted by adding physical impact due to pipe resistance, heat from the light source, and ultraviolet rays from the light source to the cleaning liquid introduced into the cleaning liquid supply mechanism, and more efficiently than before. Sufficient OH radicals can be generated in the cleaning liquid. Therefore, the cleaning effect can be enhanced as compared with the conventional case. In addition, washing can be performed with low load and low cost without using high-temperature strong acid, strong base, or the like.

At this time, the cleaning liquid is preferably ultrapure water, inorganic acid, inorganic alkali, organic acid, organic alkali, ozone water, electrolytic water, or a cleaning liquid in which two or more of these are mixed.
By using such a thing as a washing | cleaning liquid, OH radical can be produced | generated reliably in a washing | cleaning liquid, and a to-be-cleaned substrate can be cleaned effectively.

At this time, the ultraviolet light is preferably ultraviolet light having a wavelength of 200 nm to 400 nm.
If it is such a thing, sufficient OH radical can be produced | generated more efficiently and the cleaning effect can be improved more reliably.

At this time, it is preferable that the distance between the discharge port and the substrate to be cleaned is within 5 mm.
In this case, the cleaning liquid can be supplied to the substrate to be cleaned before the generated OH radicals self-extinguish, and the substrate to be cleaned can be reliably cleaned with a higher cleaning effect.

  If the cleaning method and the cleaning apparatus of the present invention are used, for example, cleaning liquid such as ozone water can be decomposed in two stages, that is, decomposition by external impact of the rectifying means, decomposition of the light source by heat and ultraviolet rays, and more efficiently. Since OH radicals can be generated in the cleaning liquid, the substrate to be cleaned can be cleaned with a cleaning liquid that has a higher cleaning effect than conventional. In addition, since it is not necessary to use a high-temperature strong acid, strong base, or the like, washing can be performed with low load and low cost.

It is sectional drawing of an example of the washing | cleaning apparatus of the to-be-cleaned substrate of this invention. It is sectional drawing which shows the cross section of the washing | cleaning apparatus in line segment A-A 'of FIG. It is sectional drawing which shows another aspect of the cross section of the washing | cleaning apparatus in line segment A-A 'of FIG. It is sectional drawing which shows the flow of the washing | cleaning liquid in the aspect of FIG. It is a figure which shows the result of an Example and a comparative example.

Hereinafter, although an embodiment is described about the present invention, the present invention is not limited to this.
As described above, a cleaning method that uses ozone water or the like as a cleaning liquid without using a cleaning liquid such as a high-temperature strong acid or strong base and generates OH radicals in the cleaning liquid improves the generation efficiency of OH radicals. It was requested.

  Therefore, the present inventor has intensively studied to solve such problems. As a result, it was conceived that OH radicals can be efficiently generated by adding a decomposition factor to the cleaning liquid continuously in two stages, and a higher cleaning effect can be obtained, thereby completing the present invention.

First, the cleaning apparatus of the present invention will be described.
As shown in FIG. 1, a cleaning apparatus 1 for a substrate to be cleaned W according to the present invention mainly includes a table 2 that supports and holds the substrate to be cleaned W and a surface to be cleaned of the substrate to be cleaned W held by the table 2. A cleaning liquid supply mechanism 3 for supplying the cleaning liquid 4 is provided. The table 2 can be provided with a rotating mechanism, whereby the held substrate W to be cleaned can be cleaned while rotating.

Here, the cleaning liquid 4 to be used is preferably ultrapure water, inorganic acid, inorganic alkali, organic acid, organic alkali, ozone water, electrolytic water, or a cleaning liquid in which two or more of these are mixed.
By using such a thing as a washing | cleaning liquid, OH radical can be produced | generated reliably in a washing | cleaning liquid, and a to-be-cleaned substrate can be cleaned effectively. Of course, the cleaning liquid is not limited to these, and any cleaning liquid may be used as long as it generates and cleans OH radicals. A strong acid, a strong base, or the like can be applied as necessary.

Here, the process of generating OH radicals will be described below, taking as an example the case of using ozone water from the above-described washing water.
Ozone water has a high oxidizing power for removing organic substances as a single substance, and can generate OH radicals having a higher oxidizing power generated in the decomposition process of ozone to remove organic substances.

The decomposition of the ozone water starts with the generation of hydrogen peroxide by the reaction of ozone and a hydroxide ion (OH ⁻ ) which is a dissociation component of water as shown in the following formula (A).
_{^{O 3 + OH - → HO 2}} - + O 2 ... (A)
HO ₂ ^{− in} the above formula (A) is a dissociation component of hydrogen peroxide. Hydrogen peroxide decomposes ozone and generates OH radicals and the like through a series of reactions shown below.
O ₃ + HO ₂ ⁻ → O ₃ ⁻ + HO ₂ (B)
O ₃ ⁻ + H ⁺ ⇔ HO ₃ (C)
HO ₃ → OH + O ₂ (D)
Thus, through the processes of the above formulas (B) to (D), ozone is finally decomposed into oxygen molecules, and OH radicals are generated in the process. However, since these radicals react or self-extinguish immediately, they do not accumulate in the solution.

  Further, as shown in FIG. 1, the cleaning liquid supply mechanism 3 includes an introduction port 5 for introducing the cleaning liquid 4 therein, a rectifying means 6 that can apply an external impact force such as pipe resistance to the cleaning liquid 4, and an ultraviolet ray on the cleaning liquid 4. The irradiation light source 7 and the discharge port 8 for discharging and supplying the cleaning liquid to the cleaning target substrate W held on the table 2 are configured.

Washing water such as ozone water is decomposed by applying decomposition factors such as external impact force, pH condition, temperature condition, absorption wavelength and the like. Therefore, in the present invention, the substrate W to be cleaned is cleaned by the cleaning apparatus 1 that can continuously give these decomposition factors.
Specifically, the rectifying means 6 and the light source 7 which are means for decomposing the cleaning liquid and generating OH radicals are installed in one cleaning liquid supply mechanism 3.

  The rectifying means 6 has a diameter of the flowing water path through which the cleaning liquid 4 passes smaller than that of the upstream flowing water path. By reducing the diameter of the flowing water path, an external impact force such as pipe resistance is applied to the cleaning liquid 4. By adding, physical decomposition of the cleaning liquid 4 can be promoted and OH radicals can be generated.

  2 corresponds to a view taken along the line A-A ′ in FIG. 1, and is a cross-sectional view showing a cross section of the cleaning device 1 along the line A-A ′ in FIG. 1. As shown in FIG. 2, for example, the rectifying means 6 has a plurality of flowing water paths 10 having a diameter smaller than that of the upstream at equal intervals around the light source 7. Pipe resistance can be added when passing. Furthermore, as shown in FIG. 2, the flowing water path 10 is arranged at equal intervals around the light source 7 so that the cleaning liquid 4 can be rectified so that it flows evenly toward the light source 7. It can be. If the cleaning liquid 4 flows uniformly toward the light source 7, thermal decomposition and photolysis of the cleaning liquid 4 by the light source 7 described later is further promoted, and OH radicals can be generated more efficiently.

  Moreover, the structure of the flowing water path 10 from the rectifying means 6 to the light source 7 can be set as shown in FIG. FIG. 3 also corresponds to a view taken along the line A-A ′ in FIG. 1, and shows a cross section of the cleaning device 1 along the line A-A ′ in FIG. 1.

As shown in FIG. 3, for example, by arranging two flowing water paths 10 symmetrically with respect to the light source 7, a swirling flow of the cleaning liquid 4 around the light source 7 can be created. Then, as shown in FIG. 4, the cleaning liquid 4 descends while turning around the light source 7, whereby the contact time of the cleaning liquid 4 with the light source 7 can be increased.
If it is such, the thermal decomposition and photolysis of the washing | cleaning liquid 4 by the light source 7 mentioned later are accelerated | stimulated more, and OH radical can be produced | generated more efficiently.

  As shown in FIGS. 1, 2, 3, and 4, the light source 7 can come into contact with the cleaning liquid 4 after the physical decomposition is promoted by the rectifying means 6. Since the light source 7 emits ultraviolet rays and the light source 7 itself generates heat, the cleaning liquid 4 can be irradiated with ultraviolet rays and heat can be conducted at the same time. Thus, the light source 7 can promote photolysis (absorption wavelength decomposition) and thermal decomposition of the cleaning liquid 4 and can generate OH radicals. The light source 7 can be a low-pressure mercury lamp whose surface is composed of a glass tube, for example. Thereby, there is also an advantage that the low-pressure mercury lamp can be cooled by the cleaning liquid.

At this time, the ultraviolet rays emitted from the light source 7 are preferably ultraviolet rays having a wavelength of 200 nm or more and 400 nm or less. Considering decomposition efficiency in particular, it is more preferable to use ultraviolet rays having a wavelength of 250 nm to 300 nm.
If it is such a thing, sufficient OH radical can be produced | generated more efficiently and the cleaning effect can be improved more reliably.

In the cleaning apparatus 1 of the present invention, the distance between the discharge port 8 and the substrate to be cleaned W held on the table 2 (the distance d shown in FIG. 1) is preferably 5 mm or less.
In this case, the cleaning liquid can be supplied to the substrate to be cleaned before the generated OH radicals self-extinguish, and the substrate to be cleaned can be reliably cleaned with a higher cleaning effect.

  As described above, the cleaning apparatus 1 of the present invention includes two means for continuously promoting the decomposition of the cleaning liquid in the cleaning liquid supply mechanism 3, so that sufficient OH radicals can be generated in the cleaning liquid more efficiently than in the past. Can be generated. Therefore, the cleaning effect can be enhanced as compared with the conventional case.

  Further, as shown in FIG. 1, by holding the cleaning liquid supply mechanism 3 with the drive arm 9, for example, the cleaning liquid supply mechanism 3 is swung and moved relative to the cleaning surface of the substrate W to be cleaned horizontally. The entire cleaning surface of the substrate to be cleaned W can be cleaned.

Next, the cleaning method of the present invention will be described. Here, the case where the cleaning apparatus 1 as shown in FIGS. 1 and 2 is used will be described.
First, the substrate to be cleaned W is held on the table 2.
The substrate to be cleaned W held at this time can be any of a photomask substrate, a quartz substrate, a Si wafer, a Ge wafer, a GaAs wafer, a SiC wafer, a flat panel, and a substrate used in the manufacturing process of a multilayer ceramic.
The cleaning method of the present invention is preferable because effective cleaning can be performed when removing organic substances adhering to these substrates.

Next, the cleaning liquid 4 is introduced into the cleaning liquid supply mechanism 3 from the introduction port 5. The cleaning liquid 4 introduced at this time can be ultrapure water, inorganic acid, inorganic alkali, organic acid, organic alkali, ozone water, electrolytic water, or a cleaning liquid in which two or more of these are mixed.
In the cleaning method of the present invention, in particular, by using these solutions as cleaning liquids, OH radicals can be reliably generated in the cleaning liquid, and the substrate to be cleaned can be effectively cleaned.

Next, piping resistance is added to the introduced cleaning liquid 4 by the rectifying means 6 described above. Furthermore, the light source 7 is brought into contact with the cleaning liquid 4 and irradiated with ultraviolet rays while the cleaning liquid is heated, thereby generating active species OH radicals in the cleaning liquid. Thus, in the present invention, the decomposition of the cleaning liquid is promoted by a two-stage decomposition process.
At this time, it is preferable that the ultraviolet rays to be irradiated are ultraviolet rays having a wavelength of 200 nm to 400 nm. Considering the decomposition efficiency in particular, it is more preferable to select a wavelength of 250 nm to 300 nm.
In this way, sufficient OH radicals can be generated more efficiently, and the cleaning effect can be improved more reliably.

In this manner, the substrate W to be cleaned is cleaned by supplying the cleaning liquid 4 containing OH radicals generated in the two-stage decomposition process from the discharge port 8.
At this time, it is preferable to supply the cleaning liquid 4 with the distance between the discharge port 8 and the substrate W to be cleaned within 5 mm.
In this way, the cleaning liquid can be supplied to the substrate to be cleaned before the generated OH radicals self-extinguish, and the substrate to be cleaned can be reliably cleaned with a higher cleaning effect.

  As described above, the cleaning method of the present invention continuously promotes the decomposition of the cleaning liquid in two steps, so that sufficient OH radicals can be generated in the cleaning liquid more efficiently than in the past. Therefore, the cleaning effect can be enhanced as compared with the conventional case.

  In particular, the cleaning method and the cleaning apparatus of the present invention include organic contaminants on the substrate to be cleaned W, positive resist, negative resist, ion implantation resist, specific organic functional layer, carbon, hydrocarbon, imprint material, tape or pellicle. It is suitable for cleaning to remove adhesive paste or paste residue, polymer foreign matter, polishing solution residue and the like.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples of the present invention, but the present invention is not limited to these.

(Examples and comparative examples)
In the embodiment, as shown in FIG. 1, using a cleaning apparatus 1 of the present invention, a chemically amplified organic component resist is applied to a thickness of 4000 nm on a 150 mm square photomask substrate by the cleaning method of the present invention. The resist film was peeled and cleaned. In the example, as shown in FIG. 3, cleaning was performed by supplying a cleaning liquid to the upper right region of the substrate.
At this time, ozone water having a dissolved ozone water concentration of 60 ppm was used as the cleaning liquid, and a low-pressure mercury lamp whose surface was formed of a glass tube was used as the light source. As this low-pressure mercury lamp, a lamp that emits light with a main wavelength of 254 nm in the ultraviolet region was selected and used. And the resist peeling amount after washing | cleaning was measured.

  In the comparative example, the same substrate as described above was cleaned under the same conditions as in the example except that a cleaning apparatus not having a mechanism for decomposing ozone water was used. In the comparative example, as shown in FIG. 3, the cleaning liquid was supplied to the upper left area of the substrate for cleaning.

As a result, as shown in FIG. 5, in the example, both the resist peeling amount and the peeling region were larger than those in the comparative example. In particular, the thickness of the substrate at the thinnest part with the largest amount of peeling was 1483 (nm) in the example and 2281 (nm) in the comparative example, confirming that the amount of peeling in the example was much larger. . Furthermore, when the volume conversion of the peeling region of the comparative example and the volume conversion of the peeling region of the example were compared, it was confirmed that the example had a resist peeling amount nearly 10 times that of the comparative example.
Thus, it was confirmed that the cleaning method and the cleaning apparatus of the present invention improve the decomposition efficiency of the organic matter on the substrate to be cleaned and increase the cleaning effect.

  The present invention is not limited to the above embodiment. The above-described embodiment is an exemplification, and the present invention has any configuration that has substantially the same configuration as the technical idea described in the claims of the present invention and that exhibits the same effects. Are included in the technical scope.

DESCRIPTION OF SYMBOLS 1 ... Cleaning apparatus, 2 ... Table, 3 ... Cleaning liquid supply mechanism,
4 ... Cleaning solution, 5 ... Inlet, 6 ... Rectification means, 7 ... Light source,
8 ... discharge port, 9 ... drive arm, 10 ... flowing water path,
W: Substrate to be cleaned.

Claims (9)

A cleaning method for cleaning a substrate to be cleaned by holding the substrate to be cleaned and supplying a cleaning liquid from a discharge port of a cleaning liquid supply mechanism onto the substrate to be cleaned.
Inside the cleaning liquid supply mechanism, a pipe resistance is added to the cleaning liquid, a light source that emits ultraviolet light is brought into contact with the cleaning liquid, and the ultraviolet light is irradiated while warming the cleaning liquid, whereby active species are contained in the cleaning liquid. A method for cleaning a substrate to be cleaned, wherein the substrate to be cleaned is cleaned by generating OH radicals of the substrate and supplying the cleaning liquid containing the OH radicals from the discharge port.   2. The substrate to be cleaned according to claim 1, wherein the cleaning liquid is ultrapure water, an inorganic acid, an inorganic alkali, an organic acid, an organic alkali, ozone water, electrolytic water, or a cleaning liquid in which two or more of these are mixed. Cleaning method.   The method for cleaning a substrate to be cleaned according to claim 1, wherein the ultraviolet light is ultraviolet light having a wavelength of 200 nm to 400 nm.   The method for cleaning a substrate to be cleaned according to any one of claims 1 to 3, wherein a distance between the discharge port and the substrate to be cleaned is within 5 mm.   2. The substrate to be cleaned is any one of a photomask substrate, a glass substrate, a Si wafer, a Ge wafer, a GaAs wafer, a SiC wafer, a flat panel, and a substrate used in a multilayer ceramic manufacturing process. The method for cleaning a substrate to be cleaned according to claim 1. A table for holding the substrate to be cleaned, and a cleaning liquid supply mechanism for introducing the cleaning liquid from the introduction port and supplying the introduced cleaning liquid to the substrate to be cleaned from the discharge port, and cleaning the substrate to be cleaned with the cleaning liquid A device,
The cleaning liquid supply mechanism includes a rectifying means for adding piping resistance to the cleaning liquid introduced from the introduction port, and a light source for heating the cleaning liquid in contact with the cleaning liquid and irradiating the cleaning liquid with ultraviolet rays. The cleaning substrate is cleaned by generating active OH radicals in the cleaning liquid by the rectifying means and the light source, and supplying the cleaning liquid containing the OH radicals from the discharge port. An apparatus for cleaning a substrate to be cleaned.   The substrate to be cleaned according to claim 6, wherein the cleaning liquid is ultrapure water, inorganic acid, inorganic alkali, organic acid, organic alkali, ozone water, electrolytic water, or a cleaning liquid in which two or more of these are mixed. Cleaning equipment.   The apparatus for cleaning a substrate to be cleaned according to claim 6 or 7, wherein the ultraviolet light has a wavelength of 200 nm to 400 nm.   The apparatus for cleaning a substrate to be cleaned according to any one of claims 6 to 8, wherein a distance between the discharge port and the substrate to be cleaned is 5 mm or less.

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