TW202241599A - Wafer cleaning method and cleaning treatment apparatus - Google Patents

Abstract

A first aspect of the present invention is a method for cleaning a wafer subjected to a polishing step, the method characterized by comprising: an ozone water treatment step for treating the wafer with ozone water after the polishing step; and a brush cleaning step for brush cleaning the wafer using a fluororesin brush, after the ozone water treatment step, wherein the brush cleaning step includes a first brush cleaning step for brush cleaning the wafer using a solution that comprises HF and an electrolyte, and a second brush cleaning step for brush cleaning the wafer using ozone water after the first brush cleaning step. Accordingly, it is possible to provide a wafer cleaning method capable of reducing the number of defects on a wafer after performing cleaning.

Description

Wafer cleaning method and cleaning processing device

The present invention relates to a wafer cleaning method and a cleaning processing device. The cleaning processing device supplies cleaning liquid to the surface of the wafer to be cleaned to perform brush cleaning.

[1st Background] In the conventional wafer cleaning process, for example, when the wafer with the abrasive attached to the surface of the wafer just after grinding is cleaned by brushing in the manner shown in Fig. 15, the wafer is treated with ozone water , Brushing with pure water, SC1 or hydrofluoric acid (HF), after removing the abrasive, perform spin cleaning or batch cleaning to repair the surface condition. For example, Patent Documents 1 to 5 describe a method and a cleaning apparatus for cleaning a wafer (substrate) using a brush.

Moreover, generally, the material of a brush is polyvinyl alcohol (PVA) (for example, patent document 1 and 2).

On the other hand, in conventional scrubbing after polishing, it is common to scrub with pure water, SC1 or HF after forming an oxide film with ozone water.

However, pure water has a low ability to remove particles, and SC1 is a chemical solution associated with anisotropic etching, and there are problems in that protrusion-shaped defects occur on the wafer surface or surface roughness deteriorates.

In addition, in the brush cleaning during HF treatment, since it is under acidic conditions, if the brush treatment is performed with HF solution from the zeta potential, although foreign matter and the like will be removed, there will be the following problems: foreign matter will adhere again, or Foreign matter leached from the brush adheres to contaminate the wafer.

In scrubbing accompanied by HF, ozone water treatment is required in order to reform the oxide film after HF treatment. The purpose of this ozone water treatment is to protect the wafer surface. If a PVA brush is used, the brush may be damaged by ozone. Damaged, thus broken.

[2nd background] In a manufacturing process of a semiconductor wafer or the like, brush cleaning is performed using a cleaning brush in order to remove foreign matter adhering to the surface of the wafer (Patent Document 1). For example, when scrubbing a wafer just after grinding, the wafer is generally treated with ozone water to form an oxide film, and then scrubbed with pure water or SC1 solution using a cleaning treatment device.

As shown in FIG. 16, as the conventional cleaning processing apparatus 101, a cleaning processing apparatus including: a cleaning liquid supply mechanism 102 for supplying the above-mentioned cleaning liquid to the surface to be cleaned of the wafer W; , the cleaning brush 103 is disposed so as to face the surface to be cleaned of the wafer W to scrub the surface to be cleaned. The cleaning brush 103 has a brush head 105 and a brush body 106 fixedly arranged on the brush head 105 . On the wafer W, the brush head 105 can rotate (autorotate) and can move in parallel in any left or right direction.

Here, the example of the brush body of the conventional cleaning brush is shown in FIG. 17, FIG. 18. As shown in FIG. 17, only one brush body is arranged on the brush head, and as shown in FIG. 18, a plurality of brush bodies are arranged. Generally speaking, the shape of the brush body is cylindrical. That is, the cross-sectional shape of the brush body is circular. In addition, generally, the material of the brush body is PVA.

In addition, when brushing the surface of the wafer to be cleaned, the removal of foreign matter attached to the wafer is carried out by rotating the wafer while supplying cleaning liquid to the wafer while moving the brush head which rotates. to make the brush body of the cleaning brush contact the wafer. Cleaning is performed by moving the wafer and the brush head so that the brush body of the cleaning brush touches the entire surface to be cleaned of the wafer for brushing. [Prior Art Literature] (patent documents)

Patent Document 1: Japanese Patent Application Laid-Open No. 10-92780 Patent Document 2: Japanese Patent Laid-Open No. 2002-96037 Patent Document 3: Japanese Patent Laid-Open No. 2003-77876 Patent Document 4: Japanese Unexamined Patent Publication No. 2014-3273 Patent Document 5: Japanese Patent Laid-Open No. 2017-175062

[Problem to be solved by the invention]

As mentioned in [1st Background], brush cleaning is generally used for wafer cleaning after polishing. Use brush cleaning to remove abrasives, etc. immediately after grinding, and then use spin cleaning or batch cleaning to modify the surface quality.

However, as described above, in the brush cleaning during the HF process, contamination of the wafer due to re-adhesion of foreign matter is a problem, and reducing the number of defects on the wafer after cleaning is a problem.

The first aspect of the present invention is made to solve the above-mentioned problems, and an object thereof is to provide a wafer cleaning method capable of reducing the number of defects on the cleaned wafer.

In addition, if the conventional cleaning treatment device as described in [Second background] is used to perform scrubbing using hydrofluoric acid (HF) or ozone water in order to improve the cleaning ability, after the HF treatment, in order to reform the oxide film , need ozone water treatment. If a brush body made of PVA is used as the brush body for cleaning the fur brush, the brush body may be damaged by ozone water and may be damaged. In addition, the brush body made of PVA has a problem of low cleaning ability (ability to remove foreign substances).

Also, as mentioned above, conventional cleaning brushes have one brush body and are not provided on the brush head, or have a cylindrical shape (circular cross-sectional shape) even if there are a plurality of brush bodies. In this case, there is a problem in that the foreign matter removed by the brush cannot be smoothly removed from the wafer and is reattached to the wafer. FIG. 19 is an explanatory view showing the range where foreign matter can be removed (removal effect range) and the position where the removed foreign matter reattaches (reattachment range) in the cylindrical brush body of the cleaning brush. The cleaning effect (the effect of removing foreign matter) is only near the edge of the front side with respect to the direction of progress (rotation direction of the brush head). Insufficient side cleaning fluid causes re-attachment of foreign matter to the wafer.

In addition, when the arrangement of the brush body is inappropriate, the cleaning liquid cannot be drained efficiently, and the cleaning liquid will remain around the brush body. From this point of view, there is also a possibility that the removed foreign matter will adhere to the wafer again. The problem.

The second aspect of the present invention is made in view of the above-mentioned problems, and an object of the present invention is to provide a cleaning treatment device that has a high cleaning effect and can suppress re-attachment of temporarily removed foreign matter. [Technical means to solve the problem]

In order to solve the above-mentioned problems related to [first background], the first aspect of the present invention provides a wafer cleaning method, which is provided for the grinding step, and the cleaning method is characterized in that it includes the following steps: an ozone water treatment step, utilizing ozone water to treat the aforementioned wafer after the aforementioned grinding step; and, Scrubbing step, after the aforementioned ozone water treatment step, use a fluororesin-based brush to scrub the aforementioned wafer; The foregoing scrubbing step includes a first scrubbing process and a second scrubbing process. The first scrubbing process uses a solution containing HF and an electrolyte to scrub the aforementioned wafer. The second scrubbing process uses ozone water after the aforementioned first scrubbing process. The aforementioned wafers were scrubbed.

According to the cleaning method of the wafer of the present invention, by using the solution containing HF and the electrolyte to brush the first brushing treatment of the wafer, foreign matter (mainly abrasive) can be suppressed from adhering to the wafer, thereby reducing the amount of damage after cleaning. The number of defects on the wafer.

In addition, since a fluororesin-based brush is used in the scrubbing step, scrubbing can also be performed in the second scrubbing process using ozone water, and the first scrubbing process using HF and the second scrubbing process using ozone water can be alternately performed. .

It is preferable to repeatedly perform the first brushing treatment and the second brushing treatment in the brushing step.

According to such a wafer cleaning method, the number of defects on the cleaned wafer can be further reduced.

In the aforementioned ozone water treatment step, the aforementioned wafer provided for the aforementioned grinding step can be brush-washed or spin-washed using ozone water.

In the ozone water treatment step performed before the first scrubbing process using HF, scrubbing or spin cleaning may be performed on the wafers provided for the polishing step.

After the aforementioned scrubbing step, a processing cleaning step of performing spin cleaning or batch cleaning on the aforementioned wafer can be further included.

After the scrubbing step, a processing cleaning step such as this can be carried out.

It is preferable to use the solution in which the concentration of the electrolyte is 0.05% by mass or more in the first brushing treatment.

By setting the concentration of the electrolyte in the solution used in the first scrubbing process to 0.05% by mass or more, it is possible to reliably prevent foreign matter from reattaching to the wafer.

Also, in order to achieve the above-mentioned object related to [Second Background], a second aspect of the present invention provides a cleaning processing apparatus including: a cleaning solution supply mechanism for supplying a cleaning solution to a surface to be cleaned of a wafer; and, A self-rotating cleaning brush, which is arranged in a manner facing the surface to be cleaned to brush the surface to be cleaned; the cleaning treatment device is characterized in that, The cleaning brush has a self-rotating brush head and a plurality of brush bodies, and the plurality of brush bodies are arranged on the brush installation surface of the brush head opposite to the surface to be cleaned of the wafer, The aforementioned plurality of brush bodies are made of fluororesin, Each cross-sectional shape of the plurality of brush bodies is any one of semicircle, L-shaped, rectangular, triangular and heart-shaped, The plurality of brush bodies are arranged radially or helically with respect to the center of the brush installation surface.

In this way, if the material of the brush body for cleaning the brush in the cleaning treatment device is fluororesin, even in the case of cleaning liquid, especially ozone water, the brush body can be prevented from being damaged and damaged. Brushing can also be performed underwater, and for example, scrubbing using HF and scrubbing using ozone water can be performed alternately, and the cleaning ability can be improved. Moreover, if the cross-sectional shape of the brush body is the above-mentioned shape, it is different from the conventional brush body with a circular cross-sectional shape, which can prevent the range of re-attachment due to insufficient cleaning liquid, and can make it substantially only have the ability to remove range of effect. Therefore, it is possible to suppress the reattachment of the foreign matter that has been removed once. In addition, since the brush bodies are installed as described above, the washing liquid introduced under the washing brushes can be drained smoothly. Therefore, it is possible to prevent the cleaning liquid from stagnating under the cleaning brush, and it is possible to suppress reattachment of the removed foreign matter due to the stagnation.

In addition, the aforementioned plurality of brush bodies can be made of polytetrafluoroethylene (PTFE), polychlorotrifluoroethylene (PCTFE), polyvinylidene fluoride (PVDF), polyvinyl fluoride (PVF), perfluoroalkoxy Any of alkanes (PFA), fluorinated ethylene-propylene copolymers (FEP), ethylene-tetrafluoroethylene copolymers (ETFE), and ethylene-chlorotrifluoroethylene copolymers (ECTFE).

With such a material, brushing under ozone water can be performed more reliably without damaging the brush body.

In addition, each of the plurality of brush bodies described above can be made into a bundle of hollow fibers or a foamed body.

If such a brush body is used, the ability to remove foreign matter can be further improved.

In addition, the cleaning liquid may be any of pure water, SC1 liquid, hydrofluoric acid, and ozone water.

In this way, pure water and SC1 liquid can be used in the same way as before, and hydrofluoric acid and ozone water can also be used, and the cleaning ability can be further improved.

Also, the aforementioned wafer can be a polished silicon wafer.

In this way, the cleaning treatment device of the present invention is particularly effective for cleaning the polished silicon wafer.

In addition, when the rotation direction of the self-rotating brush head is defined as the vertical direction, each of the plurality of brush bodies can be arranged so that the cross-sectional shape is horizontally long.

With such an arrangement, it is possible to more reliably create a removal effect range of only foreign matter, and it is possible to further effectively suppress re-attachment of foreign matter. [Efficacy of the invention]

As described above, according to the wafer cleaning method according to the first aspect of the present invention, it is possible to suppress foreign matter from adhering to the wafer, so that the number of defects on the cleaned wafer can be reduced.

In addition, as described above, according to the cleaning treatment device according to the second aspect of the present invention, it is possible to improve the cleaning effect and suppress the re-attachment of the removed foreign matter.

＜1st form＞ As described in [1st Background], it is sought to develop a wafer cleaning method capable of reducing the number of defects on a brushed wafer.

The inventors of the present invention have repeatedly studied the above-mentioned problems, and found that although foreign matter such as silicon dioxide adheres to the HF treatment of scrubbing, the zeta potential of the foreign matter and the wafer is eliminated by adding an electrolyte to the HF solution to control the zeta potential. The difference in absolute value of , whereby adhesion can be suppressed. In addition, it was found that by using a fluororesin-based brush in the brush treatment step, brush treatment can also be performed in ozone water treatment, and HF treatment and ozone water treatment can be alternately performed. The inventors of the present invention have completed the first aspect of the present invention based on these findings.

That is, the first aspect of the present invention is a wafer cleaning method provided for the grinding step, the cleaning method is characterized in that it includes the following steps: an ozone water treatment step, utilizing ozone water to treat the aforementioned wafer after the aforementioned grinding step; and, Scrubbing step, after the aforementioned ozone water treatment step, use a fluororesin-based brush to scrub the aforementioned wafer; The foregoing scrubbing step includes a first scrubbing process and a second scrubbing process. The first scrubbing process uses a solution containing HF and an electrolyte to scrub the aforementioned wafer. The second scrubbing process uses ozone water after the aforementioned first scrubbing process. The aforementioned wafers were scrubbed.

Hereinafter, the first aspect of the present invention will be described in detail with reference to the drawings, but the present invention is not limited to these descriptions.

FIG. 1 is a schematic flowchart showing an example of a wafer cleaning method according to a first aspect of the present invention.

The wafer cleaning method according to the first aspect of the present invention includes an ozone water treatment step performed on the wafer provided for the polishing step, and a subsequent scrubbing step. The example shown in Fig. 1 further includes a processing cleaning step of a scrubbing step, but this step is optional.

Each step will be described in detail below.

(grinding step) The abrasive is not particularly limited, and for example, silica can be used. For example, by using an abrasive having a silica particle having a primary particle diameter of 10 nm to 35 nm and a silica concentration of 0.01 mass % to 1.0 mass %, it can be removed by brushing.

The polishing conditions are not particularly limited, and conditions suitable as polishing conditions for wafers can be applied.

(Ozone water treatment steps) The ozone water treatment step is to use ozone water to treat the wafer after the grinding step. In this ozone water treatment step, it is possible to decompose the organic matter attached to the abrasive on the wafer by performing ozone water treatment on the wafer with the abrasive attached to the entire surface immediately after polishing, for example, by brush cleaning or spin cleaning. removal, and oxide film formation.

The concentration of ozone water used in this ozone water treatment step is preferably not less than 10 ppm and not more than 50 ppm. The cleaning time is preferably from 10 seconds to 60 seconds. When performing spin cleaning, it is preferable to set the rotation speed of the wafer to 5 rpm or more and 60 rpm or less. The flow rate of ozone water in the ozone water treatment step is preferably set to 0.8 L/min or more and 4.0 L/min or less.

The ozone water treatment step is preferably carried out under the condition that the thickness of the formed oxide film is 0.5 nm to 1.5 nm.

In the ozone water treatment step, one treatment with ozone water may be performed, and multiple treatments may be performed.

(Scrubbing step) In the scrubbing step, after the ozone water treatment step, the wafer is scrubbed with a fluororesin-based brush. This scrubbing step includes a first scrubbing process and a second scrubbing process, the first scrubbing process uses a solution containing HF and an electrolyte to scrub the wafer, and the second scrubbing process uses ozone water to scrub after the aforementioned first scrubbing process wafer.

By using the fluorine-based resin brush, brushing can be performed even in the cleaning process using ozone water, and the first brushing process using HF and the second brushing process using ozone water can be alternately performed. Therefore, the wafer cleaning method according to the first aspect of the present invention can repeatedly perform the first scrubbing process and the second scrubbing process. By repeatedly performing the first scrubbing process and the second scrubbing process, the number of defects on the cleaned wafer can be further reduced.

As the brush of fluororesin, for example, a brush obtained by bundling hollow fibers made of fluororesin such as PTFE, PCTFE, PVDF, PVF, PFA, FEP, ETFE, and ECTFE, or a brush with a foam structure can be used. .

Hereinafter, the first scrubbing process and the second scrubbing process will be described in detail.

＜1st brushing process＞ In the first scrubbing process, the wafer is scrubbed using a solution containing HF and an electrolyte.

Here, for example, physical cleaning is performed by brush washing using a solution obtained by adding HF at a concentration of 1.0% by mass or less and electrolyte at a concentration of 0.05% by mass or more to pure water. The upper limit of the amount of electrolyte added is not particularly limited, but it can be 10% by mass or less in consideration of the solubility and cost of the electrolyte.

By adding the electrolyte to the HF solution, the zeta potential can be controlled, and foreign matter can be suppressed from adhering to the wafer in the first scrubbing process using HF. As a result, the number of defects on the cleaned wafer can be reduced.

By using a solution having an electrolyte concentration of 0.05% by mass or more, it is possible to more reliably suppress the adhesion of foreign substances in the first brushing process.

Examples of electrolytes include NaCl, NaClO, KCl, KClO, NaOH, KOH, NH ₄ OH, NH ₄ Cl, NH ₄ F, formamide, formic acid, acetic acid, oxalic acid, malic acid, tartaric acid, and citric acid.

The first brushing treatment time is preferably set to a time that can be treated so that the oxide film is removed and the surface is not exposed. For example, the cleaning time is preferably set to 5 seconds or more and 60 seconds or less. For example, the HF flow rate is preferably set at 0.8 L/min or more and 4.0 L/min or less.

The rotation speed of the fur brush in the first brushing process is not particularly limited, for example, it can be set to 5 rpm or more and 200 rpm or less.

It is also possible to perform the first scrubbing process while rotating the wafer. The rotational speed of the wafer at this time can be, for example, not less than 5 rpm and not more than 60 rpm. The rotation direction of the wafer is not particularly limited. The rotation direction of the brush is not particularly limited. For example, the rotation direction of the wafer can be set to a counterclockwise direction (CCW), and the rotation direction of the brush can be set to a clockwise direction (CW). Alternatively, both may be clockwise or counterclockwise.

＜Second scrubbing treatment＞ In the second scrubbing process, the wafer is scrubbed with ozone water after the first scrubbing process.

By this second scrubbing process, an oxide film as a protective film can be formed on the surface of the wafer.

The concentration of ozone water used in this second scrubbing process is preferably not less than 10 ppm and not more than 50 ppm. The cleaning time is preferably set to 10 seconds or more and 180 seconds or less. When performing spin cleaning, it is preferable to set the rotation speed of the wafer to 5 rpm or more and 60 rpm or less. The flow rate of ozone water in the ozone water treatment step is preferably set to 0.8 L/min or more and 4.0 L/min or less.

The second brushing treatment is preferably carried out under the condition that the formed oxide film has a thickness of not less than 0.5 nm and not more than 1.5 nm.

The rotation speed of the fur brush in the second brushing process is not particularly limited, and can be, for example, 5 rpm or more and 200 rpm or less.

It is also possible to perform the second brushing process while rotating the wafer. The rotational speed of the wafer at this time can be, for example, not less than 5 rpm and not more than 60 rpm. The rotation direction of the brush with respect to the rotation direction of the wafer is not particularly limited.

As described above, the first cleaning process and the second cleaning process can be repeatedly performed. All washing conditions may be set to be the same for each time, or may be set to mutually different conditions.

(processing and cleaning steps) The process cleaning step, which is an optional step in the first aspect of the present invention, is a step of performing spin cleaning or batch cleaning on the wafer after the brush cleaning step.

In the processing and cleaning steps, for example, cleaning with ozone water, rinsing with pure water, cleaning with chemical solution, cleaning with ozone water, and rinsing with pure water can be performed in sequence, but not limited to this.

The concentration of ozone water used for each cleaning with ozone water can be, for example, not less than 5 ppm and not more than 40 ppm. The cleaning time with ozone water can be, for example, not less than 10 seconds and not more than 60 seconds. When washing with ozone water is performed by spin washing, the rotation speed can be set to, for example, 5 rpm or more and 60 rpm or less. The flow rate of ozone water can be, for example, not less than 0.8 L/min and not more than 4.0 L/min.

When each rinsing with pure water is performed by spin washing, the rotational speed of the pure water rotation can be set to, for example, 100 rpm or more and 1500 rpm or less. The flow rate of pure water can be, for example, not less than 0.8 L/min and not more than 4.0 L/min. The pure water rinsing time can be, for example, not less than 5 seconds and not more than 60 seconds.

When cleaning with chemical solution is performed by spin cleaning, the rotation speed of chemical solution can be set, for example, to 100 rpm or more and 1500 rpm or less. As the liquid medicine, for example, HF, SC1 or SC2 can be used. The concentration of the chemical solution can be, for example, not less than 0.1% by mass and not more than 5.0% by mass. The flow rate of the chemical solution can be, for example, not less than 0.8 L/min and not more than 4.0 L/min. The cleaning time by the chemical solution can be set to, for example, 5 seconds or more and 60 seconds or less.

When HF (hydrofluoric acid) is used as the chemical solution, by spin cleaning or batch cleaning after scrubbing, for example, after removing the oxide film by hydrofluoric acid treatment, the oxide film can be reformed by ozone water treatment.

After the process cleaning step, a step of drying the wafer may be included.

In addition, the wafer to be cleaned in the wafer cleaning method according to the first aspect of the present invention is not particularly limited, and for example, a semiconductor single crystal silicon wafer can be used as the cleaning target.

＜Second aspect＞ As described in [Second Background], in a wafer cleaning processing apparatus that cleans a wafer by scrubbing using a cleaning brush, there are problems in terms of low cleaning performance and reattachment of foreign matter. Therefore, the present inventors devoted themselves to conducting research, and found that the plurality of brush bodies in the cleaning brush, if the material is fluororesin, each cross-sectional shape is any one of semicircle, L-shape, rectangle, triangle, and heart shape. If it is arranged in a radial or helical manner relative to the center of the brush installation surface, it can also be scrubbed under ozone water, which can improve the cleaning ability and prevent foreign matter from reattaching, thereby completing the first aspect of the present invention. 2 styles.

Hereinafter, an embodiment of the second aspect of the present invention will be described with reference to the drawings, but the second aspect of the present invention is not limited thereto. Fig. 2 shows an example of a cleaning treatment device according to a second aspect of the present invention. The cleaning treatment device 1 is a paddle-type device, and includes a cleaning liquid supply mechanism 2 and a cleaning brush 3 . In addition, this cleaning processing apparatus 1 includes a wafer holder 4 capable of holding a wafer W to be cleaned.

The wafer to be cleaned by the cleaning processing apparatus 1 of the second aspect of the present invention is not particularly limited, and examples thereof include various semiconductor wafers such as semiconductor silicon wafers and compound semiconductor wafers; round. In addition, this cleaning processing apparatus 1 is an apparatus which can also clean various wafer-shaped objects, such as a glass substrate.

The wafer holder 4 can be rotatable by a driving source not shown, and the wafer W held can be rotatable by this rotation. For example, the same conventional wafer holder can be used. In addition, as shown in FIG. 2 , the cleaning liquid supply mechanism 2 can be, for example, a nozzle. This nozzle supplies cleaning liquid to the surface S to be cleaned of the wafer W held by the wafer holder 4 . Examples of the cleaning liquid include pure water and SC1 liquid that have been generally used in conventional cleaning. Furthermore, HF or ozone water can also be supplied. As described below, the cleaning brush 3 in the second aspect of the present invention is particularly resistant to ozone water, and HF and ozone water can also be alternately supplied during brushing in order to improve the cleaning ability and re-form the oxide film. . In addition, an example of the nozzle has been described as the cleaning liquid supply mechanism 2 , but it is also possible to adopt an aspect in which it is integrated with the cleaning brush 3 and can discharge the cleaning liquid from the lower part of the cleaning brush 3 .

Cleaning brush 3 is located above wafer W and arranged to face surface S of wafer W to be cleaned. The aforementioned cleaning brush 3 has a brush head 5 and a plurality of brush bodies 6, the brush head 5 has a brush setting surface B opposite to the surface S to be cleaned, and the plurality of brush bodies 6 are arranged on the brush setting surface B . Then, this brush body 6 is brought into contact with the surface S to be cleaned to perform brush cleaning.

The brush head 5 can be rotated by a driving source not shown, and the brush body 6 fixed to the brush installation surface B rotates together with the rotation of the brush head 5 .

Moreover, the material of the brush body 6 is a fluororesin. Conventional brush bodies made of PVA may be damaged and broken under ozone water. However, as described in the second aspect of the present invention, the brush body 6 made of fluororesin is resistant to ozone water, and is not damaged by damage like conventional products. Therefore, it is also possible to alternately use HF ozone water to perform scrubbing. At this time, it is possible to select from PTFE, PCTFE, PVDF, PVF, PFA, FEP, ETFE, ECTFE, etc., and brushing under ozone water can be performed more reliably without damaging the brush body 6 . In addition, the brush body made of fluororesin inherently has a higher cleaning ability than the brush body made of PVA.

Moreover, as this brush body 6, each can be comprised by the bundle|flux of hollow fibers, for example. The number of wires per bundle is not particularly limited, and can be, for example, several tens to several hundreds. Moreover, instead of the bundle of hollow fibers, it can also be set as a foam. If it is such a brush body, the ability to remove foreign matter will be improved.

Moreover, the shape of the brush body 6 is also characteristic. The shape of the device in the past is cylindrical, that is, the cross-sectional shape is circular, but the cross-sectional shape of the brush body 6 in the second aspect of the present invention is one of semicircle, L-shaped, rectangular, triangular and heart-shaped. any kind. Examples of these shapes are shown in FIGS. 3 to 7 . Here, when the cross-sectional shape is circular as in the past, as shown in FIG. 19, foreign matter can be removed on the front side (removal effect range) with respect to the rotation direction of the self-rotating brush head, but the rear side is affected by cleaning. Insufficient liquid causes the re-adhesion of the removed foreign matter to occur again. On the other hand, in the case of the second aspect of the present invention, since it is a semicircle rather than a circle, as shown in FIG. 8, it becomes a shape that substantially only has the range of the removal effect, and it is possible to suppress recurrence. Occurrence of attached range. Therefore, it is possible to suppress re-attachment of the once-removed foreign matter, which has been a problem in conventional cleaning devices. In addition, although the example of the case of a semicircle is shown in FIG. 8, even other shapes (L shape, rectangle, triangle, heart shape) can similarly have only the removal effect range.

Furthermore, a plurality of brush bodies 6 as described above are arranged in a row on the brush installation surface B of the brush head 5 in a radial or helical shape with respect to the center of the brush installation surface B. Fig. 9 shows a radial arrangement pattern and Fig. 10 shows a helical arrangement pattern (in the upper left corner respectively). In addition, the example at the time of providing the brush body 6 whose cross-sectional shape is the shape of FIG. 3 - FIG. 7 is also shown together. With the radial or helical arrangement, the cleaning liquid introduced between the cleaning brush 3 (brush head 5 ) and the wafer W can be efficiently discharged during the cleaning process. That is, foreign matter removed by brushing with the cleaning brush 3 can also be smoothly discharged together with the cleaning liquid. Therefore, it is possible to prevent the cleaning liquid from stagnating between the cleaning brush and wafer W. Therefore, it is possible to prevent the removed foreign matter from reattaching due to stagnation of the washing liquid.

In addition, the number of brush bodies 6 provided on the brush installation surface B is not specifically limited as long as it is plural. It can be appropriately determined according to the size of the brush installation surface B, the size of each brush body 6 , the type of wafer W to be cleaned, the type of cleaning liquid, and the like.

Also, there is no particular limitation on the way in which the brush body 6 is arranged on the brush installation surface B, but it is particularly preferred that the cross-sectional shape of the brush body 6 be horizontally long with respect to the rotation direction (rotation direction) of the brush head 5. direction setting. Here, as an example, FIG. 11 shows the installation direction of the brush body 6 with respect to the rotation direction (autorotation direction) of the brush head 5 when the cross-sectional shape of the brush body 6 is rectangular. As shown in the plan view of FIG. 11, when the rotation direction of the brush head 5 is defined as the vertical direction (the upward direction in the drawing), the long side of the rectangle (cross-sectional shape) becomes the horizontal direction (the left-right direction in the drawing). , so that the entire cross-sectional shape is provided with the brush body 6 in the horizontally long direction. In addition, although the example which installed so that the long side may perpendicularly intersect with the rotation direction of the brush head 5 was shown, Of course, you may incline by shifting an angle. Also in the case of other cross-sectional shapes, each brush body 6 can be similarly provided in the horizontally long direction. If it is installed in such a direction, it is possible to more reliably create a range that only has a removal effect range and does not have re-adhesion, and can further effectively suppress re-adhesion of foreign matter.

An example of a cleaning process step including scrubbing of a wafer using the cleaning processing apparatus 1 according to the second aspect of the present invention as described above will be described. First, for example, a wafer W (silicon wafer, etc.) is prepared and held by the wafer holder 4 of the cleaning processing apparatus 1. After the wafer W is subjected to a grinding process, it is adhered to the surface by ozone water treatment. The decomposition and removal of organic matter in abrasives and the formation of oxide films.

The brush body 6 of the cleaning fur brush 3 is brought into contact with the surface S to be cleaned while HF as the cleaning liquid is supplied to the surface S to be cleaned from the nozzle of the cleaning liquid supply mechanism 2 to perform brushing. At this time, the cleaning brush 3 is rotated on its own and simultaneously moved in parallel on the wafer W, thereby scrubbing the entire surface S to be cleaned. The concentration of HF to be supplied can be, for example, 1.0% by mass or less, but is not particularly limited. The cleaning treatment time is preferably set to a time that can be processed so that the oxide film is removed and the surface is not exposed. For example, it can be 5 seconds or more and 60 seconds or less. The HF flow rate can be, for example, not less than 0.8 L/min and not more than 4.0 L/min. The rotation speed of the cleaning brush 3 is not particularly limited, and can be, for example, not less than 5 rpm and not more than 200 rpm.

Furthermore, during the scrubbing, the wafer W itself may or may not be rotated. When rotating, the rotational speed of the wafer W can be, for example, not less than 5 rpm and not more than 60 rpm. The rotation direction of the wafer W is not particularly limited. The rotation direction of the cleaning brush 3 is not particularly limited. For example, the rotation direction of the wafer W can be set to a counterclockwise direction (CCW), and the rotation direction of the cleaning brush 3 can be set to a clockwise direction (CW). Alternatively, both may be clockwise or counterclockwise.

Then, ozone water is supplied instead of HF to perform scrubbing. The concentration of the supplied ozone water can be set to, for example, not less than 10 ppm and not more than 50 ppm. The cleaning time can be, for example, not less than 10 seconds and not more than 180 seconds. The ozone water flow rate can be set to, for example, not less than 0.8 L/min and not more than 4.0 L/min. The rotation speed of the cleaning brush 3 is not particularly limited, and can be, for example, not less than 5 rpm and not more than 200 rpm. The rotation of the wafer W itself can be, for example, the same as that in the case of performing brush cleaning by HF described above. It is preferable to carry out under the condition that the thickness of the oxide film formed in this step becomes 0.8 nm or more and 1.5 nm or less.

Such scrubbing with HF and scrubbing with ozone water can be repeated alternately as necessary. The cleaning conditions for each time may be all the same or may be different from each other.

In addition, pure water or SC1 liquid can be used for brushing at an appropriate timing as needed. After brush cleaning is performed using the cleaning treatment apparatus 1 of the second aspect of the present invention as described above, as process cleaning, for example, spin cleaning or batch cleaning can be performed. In these cleanings, after removal of the oxide film with HF, in particular, ozone water can be used to reform the oxide film.

By the cleaning process as described above, foreign matter can be efficiently removed and reattachment thereof can be suppressed, so that a wafer W with a high degree of cleanliness can be obtained. [Example]

Hereinafter, although the 1st aspect of this invention is demonstrated concretely using an Example and a comparative example, the 1st aspect of this invention is not limited to these examples.

In the following Comparative Examples and Examples 1 to 7, the wafer (P-type single crystal silicon wafer with a diameter of 300 mm) was cleaned in the procedure described below. The temperature of the chemical|medical solution and pure water used in the comparative example and the Example was set to room temperature (25 degreeC). The number of defects on the wafer after cleaning was measured by counting particles having a particle diameter of 19 nm or more using SP5 (trade name) manufactured by KLA-Tencor Corporation.

(comparative example) In the comparative example, the wafer was cleaned according to the cleaning flow shown in FIG. 12 . Specifically, first, the wafer is ground (polishing step). The conditions of the grinding step are shown in Table 1 below.

[Table 1]

Then, using the ozone water treatment step, the ozone water treatment is performed on the ground wafer with the abrasive adhered thereto. Ozone water treatment uses ozone water for spin cleaning, and then uses ozone water for scrubbing. The conditions of the ozone water treatment step are shown in Table 2 below.

[Table 2]

Next, the wafer is brushed using an HF solution (brushing process (HF)). Brushing is performed while rotating the brush and the wafer (HF). The conditions of the brushing treatment (HF) are shown in Table 3 below.

[table 3]

Next, the wafer is scrubbed using ozone water (brushing treatment (ozone water)). Scrubbing (ozone water) was performed while rotating the brush and the wafer. The conditions of the scrubbing treatment (ozone water) are shown in Table 4 below.

[Table 4]

The scrubbing treatment (HF) described above and the subsequent scrubbing treatment (ozone water) were repeated three times under the conditions described in Table 3 and Table 4, respectively, and then spin cleaning was performed as processing cleaning.

In the spin washing, spin washing using ozone water, rinsing with pure water, spin washing using chemical solution, spin washing using ozone water, and rinsing with pure water are performed in this order. Next, the spin-cleaned wafer is dried. The conditions of spin washing and drying are summarized in Table 5 below.

[table 5]

(Embodiments 1-7) In Examples 1 to 7, the wafer was cleaned according to the cleaning flow shown in FIG. 13 . Specifically, in Examples 1 to 7, after the ozone water treatment step, a scrubbing treatment using a solution containing HF and NaCl (first scrubbing treatment (HF+NaCl)) was performed instead of the scrubbing treatment performed in Comparative Example (HF), then, implement the same scrubbing process (the 2nd scrubbing process (ozone water)) as the scrubbing process (ozone water) of the comparative example, repeatedly implement this 1st scrubbing process and the 2nd scrubbing process 3 times, except this In addition, cleaning of the wafer was carried out under the same conditions as in the comparative example.

The conditions of the first brushing treatment in Examples 1 to 7 are shown in Table 6 below.

[Table 6]

(Evaluate) FIG. 14 shows the evaluation results of the number of wafer defects after cleaning in the comparative example and Examples 1 to 7. In FIG.

It can be seen from FIG. 14 that, compared with the comparative example, the number of defects on the wafer after cleaning in Examples 1 to 7 is reduced, and the number of defects is improved.

In the comparative example, since no electrolyte was added to the HF solution used in the scrubbing process (HF), it is considered that foreign matter reattached to the wafer during this process, and the number of defects increased.

In addition, in Examples 1 to 7, a fluororesin-based fur brush was used for scrubbing, so scrubbing can be performed without any problem even in ozone water treatment.

In addition, this invention is not limited to the said embodiment. The above-mentioned embodiments are examples, and any one having substantially the same configuration as the technical idea described in the claims of the present invention and exerting the same effects is included in the technical scope of the present invention.

1,101: Cleaning treatment unit 2,102: cleaning fluid supply mechanism 3,103: cleaning brush 4:Wafer holder 5,105: brush head 6,106: brush body B: brush setting surface S: Surface to be cleaned W: Wafer 101: Conventional cleaning treatment device

FIG. 1 is a schematic flowchart showing an example of a wafer cleaning method according to a first aspect of the present invention. Fig. 2 is a schematic diagram showing an example of a cleaning treatment device according to a second aspect of the present invention. Fig. 3 is an explanatory diagram showing an example of a semicircular cross-sectional shape of a brush body. Fig. 4 is an explanatory diagram showing an example of the L-shaped cross-sectional shape of the brush body. Fig. 5 is an explanatory diagram showing an example of a rectangular cross-sectional shape of a brush body. Fig. 6 is an explanatory diagram showing an example of a triangular cross-sectional shape of a brush body. Fig. 7 is an explanatory diagram showing an example of a heart-shaped cross-sectional shape of the brush body. Fig. 8 is an explanatory diagram showing an example of the removal effect range when the cross-sectional shape is a semicircular brush body. Fig. 9 is an explanatory diagram showing an example of a radial arrangement pattern. Fig. 10 is an explanatory diagram showing an example of a spiral arrangement pattern. Fig. 11 is an explanatory diagram in plan view showing an example of the installation direction of the brush body with respect to the rotation direction (autorotation direction) of the brush head when the cross-sectional shape of the brush body is rectangular. FIG. 12 is a schematic flowchart of a wafer cleaning method of a comparative example. Fig. 13 is a schematic flow chart of the wafer cleaning method in Examples 1 to 7. FIG. 14 is a graph showing the evaluation results of the number of wafer defects after cleaning in Comparative Example and Examples 1 to 7. FIG. FIG. 15 is a schematic flowchart showing an example of a conventional wafer cleaning method. Fig. 16 is a schematic diagram showing an example of a conventional cleaning treatment device. Fig. 17 is a schematic diagram showing an example of the shape of a brush body in a conventional cleaning brush. Fig. 18 is an explanatory diagram showing another example of the shape of the brush body in the conventional cleaning brush. Fig. 19 is an explanatory view showing an example of the positions of the effective range of removing foreign matter and the reattachment range of foreign matter in a columnar brush body. The left side shows the position when the cleaning brush is viewed from the side, and the right side shows the position in the planar view of the brush body.

Domestic deposit information (please note in order of depositor, date, and number) none Overseas storage information (please note in order of storage country, institution, date, and number) none

Claims (11)

A method for cleaning a wafer, which is provided for the grinding step, is characterized in that it comprises the following steps: an ozone water treatment step, utilizing ozone water to treat the aforementioned wafer after the aforementioned grinding step; and, Scrubbing step, after the aforementioned ozone water treatment step, use a fluororesin-based brush to scrub the aforementioned wafer; The foregoing scrubbing step includes a first scrubbing process and a second scrubbing process. The first scrubbing process uses a solution containing HF and an electrolyte to scrub the aforementioned wafer. The second scrubbing process uses ozone water after the aforementioned first scrubbing process. The aforementioned wafers were scrubbed. The wafer cleaning method according to claim 1, wherein the first brushing process and the second brushing process are repeatedly performed in the brushing step. The wafer cleaning method according to claim 1, wherein, in the ozone water treatment step, ozone water is used to brush or spin clean the wafer provided for the grinding step. The wafer cleaning method according to claim 1, further comprising a processing and cleaning step of performing spin cleaning or batch cleaning on the wafer after the brush cleaning step. The wafer cleaning method according to any one of claims 1 to 4, wherein the solution having a concentration of the electrolyte of 0.05% by mass or more is used in the first scrubbing process. A cleaning treatment device comprising: a cleaning solution supply mechanism for supplying cleaning solution to a surface to be cleaned of a wafer; Cleaning surface; the cleaning treatment device is characterized in that, The cleaning brush has a self-rotating brush head and a plurality of brush bodies, and the plurality of brush bodies are arranged on the brush installation surface of the brush head opposite to the surface to be cleaned of the wafer, The aforementioned plurality of brush bodies are made of fluororesin, Each cross-sectional shape of the plurality of brush bodies is any one of semicircle, L-shaped, rectangular, triangular and heart-shaped, The plurality of brush bodies are arranged radially or helically with respect to the center of the brush installation surface. The cleaning treatment device according to claim 6, wherein the materials of the plurality of brush bodies are polytetrafluoroethylene, polychlorotrifluoroethylene, polyvinylidene fluoride, polyvinyl fluoride, perfluoroalkoxyalkane, fluorine Any of ethylene-propylene copolymers, ethylene-tetrafluoroethylene copolymers, and ethylene-chlorotrifluoroethylene copolymers. The cleaning treatment device according to claim 6, wherein each of the plurality of brush bodies is a bundle of hollow fibers or a foam body. The cleaning treatment device according to claim 6, wherein the cleaning liquid is any one of pure water, SC1 liquid, hydrofluoric acid, and ozone water. The cleaning processing device according to claim 6, wherein the wafer is a ground silicon wafer. The cleaning treatment device according to any one of Claims 6 to 10, wherein when the rotation direction of the self-rotating brush head is set as the vertical direction, each of the plurality of brush bodies is such that the cross-sectional shape is horizontally long. direction setting.

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