KR20230173091A - Wafer cleaning method and cleaning processing device - Google Patents

Abstract

A first aspect of the present invention is a method of cleaning a wafer subjected to a polishing process, comprising: an ozone water treatment process of treating the wafer with ozonated water after the polishing process; and, after the ozone water treatment process, the wafer is treated with a fluororesin brush. and a brush cleaning process of brush cleaning, wherein the brush cleaning process includes a first brush cleaning process of brush cleaning the wafer using a solution containing HF and an electrolyte, and, after the first brush cleaning process, using ozonated water. A wafer cleaning method comprising a second brush cleaning process for brush cleaning the wafer. As a result, it is possible to provide a wafer cleaning method that can reduce the number of defects on the wafer after cleaning.

Description

Wafer cleaning method and cleaning processing device

The present invention relates to a wafer cleaning method and a cleaning processing device for performing brush cleaning by supplying a cleaning liquid to the surface to be cleaned of the wafer.

[First background]

In the conventional wafer cleaning flow, for example, as shown in Figure 15, when a wafer with an abrasive adhering to the surface of the wafer immediately after polishing is cleaned by brush cleaning, the wafer is treated with ozonated water and then brush cleaned with pure water or SC1 or HF. After removing the abrasive, spin cleaning or batch cleaning is performed to finish the surface condition. For example, Patent Documents 1 to 5 describe a method and cleaning device for cleaning a wafer (substrate) using a brush.

Additionally, the material of the brush is generally PVA (for example, Patent Documents 1 and 2).

However, in conventional brush cleaning after polishing, it is common to form an oxide film with ozone water and then clean the brush with pure water, SC1, or HF.

However, pure water had a low ability to remove particles, and since SC1 is a chemical solution that involves anisotropic etching, there were problems such as protruding defects occurring on the wafer surface and surface roughness deteriorating.

In addition, since the brush cleaning during HF treatment is under acidic conditions, when brushing with an HF solution from zeta potential removes foreign substances, etc., foreign substances re-attach or foreign substances eluted from the brush adhere, contaminating the wafer. There was a problem.

In brush cleaning involving HF, ozone water treatment is required to reform the oxide film for the purpose of protecting the wafer surface after HF treatment, and if a PVA brush is used, the brush may be damaged by ozone and may be damaged. .

[Second background]

During the manufacturing process of semiconductor wafers, etc., brush cleaning is performed using a cleaning brush to remove foreign substances adhering to the wafer surface (Patent Document 1). For example, when brush cleaning a wafer immediately after polishing, it is common to treat the wafer with ozone water to form an oxide film and then brush clean it with pure water or SC1 liquid using a cleaning treatment device.

As shown in FIG. 16, this conventional cleaning apparatus 101 includes a cleaning liquid supply mechanism 102 for supplying the above-mentioned cleaning liquid to the surface to be cleaned of the wafer W, and One example includes a cleaning brush 103 arranged oppositely to brush clean the surface to be cleaned.

The cleaning brush 103 has a brush head 105 and a brush body 106 fixed to the brush head 105. On the wafer W, the brush head 105 can rotate (rotate) and move in parallel in any left or right direction.

Here, Figures 17 and 18 show examples of brush bodies in conventional cleaning brushes. In some cases, only one brush body is provided relative to the brush head, as shown in Fig. 17, and in other cases, multiple brush bodies are provided in relation to the brush head, as shown in Fig. 18, but the shape of the brush bodies is generally cylindrical. That is, the cross-sectional shape of the brush body is circular.

Additionally, the material of the brush body is generally PVA.

Then, when brush cleaning the surface to be cleaned of the wafer, the wafer is rotated and the rotating brush head is moved while supplying the cleaning liquid onto the wafer, thereby bringing the brush body of the cleaning brush into contact with the wafer to remove foreign matter adhering to the wafer. perform removal. Cleaning is performed while moving the wafer and the brush head so that the brush body of the cleaning brush contacts the entire surface to be cleaned of the wafer and brush cleans it.

Japanese Patent Publication No. H10-92780 Japanese Patent Publication No. 2002-96037 Japanese Patent Publication No. 2003-77876 Japanese Patent Publication No. 2014-3273 Japanese Patent Publication No. 2017-175062

As explained in [First Background], brush cleaning is generally used to clean wafers after polishing. Brush cleaning removes abrasives immediately after polishing, and then spin cleaning or batch cleaning finishes the surface quality.

However, as explained above, in brush cleaning during HF processing, contamination of the wafer due to re-adhesion of foreign substances, etc. is a problem, and reducing the number of defects on the wafer after cleaning has been a problem.

The first aspect of the present invention was made to solve the above problem, and its purpose is to provide a wafer cleaning method that can reduce the number of defects on the wafer after cleaning.

In addition, when using a conventional cleaning device as described in [Second Background] and attempting to perform brush cleaning using hydrofluoric acid (HF) or ozonated water to improve cleaning ability, oxide film reformation occurs after HF treatment. Ozone water treatment is required for this purpose. If a brush made of PVA was used as the brush body of the cleaning brush, the brush body would be damaged by ozonated water, and there was a possibility that it could be damaged.

Additionally, the brush body made of PVA has a problem of low cleaning ability (ability to remove foreign substances).

In addition, as described above, the conventional cleaning brush has one brush body and no discharge pattern to the brush head, or even when there are multiple brush bodies, it is cylindrical (the cross-sectional shape is circular). In this case, there was a problem in that the foreign matter removed by the brush body was not smoothly removed from the wafer and re-attached to the wafer.

FIG. 19 is an explanatory diagram showing the positions of the range in which foreign matter can be removed (removal effect range) and the range in which reattachment of the removed foreign matter occurs (reattachment range) on the cylindrical brush body of the cleaning brush. am. The cleaning effect (foreign matter removal effect) is only found near the front edge with respect to the direction of travel (the direction of rotation of the brush head). In the case of no pattern or a cylindrical brush body, the cleaning liquid is insufficient at the rear of the brush body. This causes re-adhesion of foreign substances to the wafer.

Additionally, if the drainage pattern of the brush body is not appropriate, the cleaning liquid cannot be drained efficiently and the cleaning liquid stays around the brush body. In this regard as well, there is a problem in that the removed foreign matter re-adheres to the wafer.

The second aspect of the present invention has been made in view of the above-mentioned problems, and its purpose is to provide a cleaning device that has a high cleaning effect and can suppress the occurrence of re-adhesion of foreign substances once removed.

In order to solve the above problem regarding [First Background], in a first aspect of the present invention, there is provided a method for cleaning a wafer subjected to a polishing process, comprising:

After the polishing process, an ozone water treatment process for treating the wafer with ozonated water;

After the ozone water treatment process, a brush cleaning process of brush cleaning the wafer using a fluorine resin brush.

Including,

The brush cleaning process includes a first brush cleaning process in which the wafer is brush cleaned using a solution containing HF and an electrolyte, and, after the first brush cleaning process, a second brush cleaning process in which the wafer is brush cleaned using ozonated water. A wafer cleaning method comprising processing is provided.

According to the wafer cleaning method of the present invention, the first brush cleaning process of brush cleaning the wafer using a solution containing HF and electrolyte can prevent foreign substances (mainly abrasives) from adhering to the wafer, so the cleaning The number of defects on later wafers can be reduced.

In addition, since a fluororesin brush is used in the brush cleaning process, brush cleaning is possible even during the second brush cleaning treatment using ozonated water, and the first brush cleaning treatment using HF and the second brush cleaning treatment using ozonated water are alternately performed. It can be done.

In the brush cleaning process, it is preferable to repeat the first and second brush cleaning processes.

According to this wafer cleaning method, the number of defects on the wafer after cleaning can be further reduced.

In the ozone water treatment process, the wafer subjected to the polishing process can be brush cleaned or spin cleaned using ozonated water.

In the ozone water treatment process performed before the first brush cleaning process using HF, the wafer subjected to the polishing process may be brush cleaned or spin cleaned.

After the brush cleaning process, a final cleaning process of spin cleaning or batch cleaning the wafer may be additionally included.

After the brush cleaning process, this final cleaning process can be performed, for example.

In the first brush cleaning treatment, it is preferable to use the solution having a concentration of the electrolyte of 0.05% by mass or more.

By setting the electrolyte concentration of the solution used in the first brush cleaning treatment to 0.05% by mass or more, re-adhesion of foreign substances to the wafer can be more reliably prevented.

In addition, in order to achieve the above object regarding the [second background], the second aspect of the present invention includes a cleaning liquid supply mechanism for supplying a cleaning liquid to the surface to be cleaned of a wafer, and a cleaning liquid supply mechanism disposed opposite to the surface to be cleaned to clean the surface to be cleaned. A cleaning processing device equipped with a rotatable cleaning brush for brush cleaning,

The cleaning brush has a rotatable brush head and a plurality of brush bodies disposed on a brush discharge surface of the brush head that faces the surface to be cleaned of the wafer,

The plurality of brush bodies are,

The material is fluororesin,

Each cross-sectional shape is one of semicircular, L-shaped, rectangular, triangular, and heart-shaped,

A cleaning treatment device is provided, wherein the brush is discharged side by side in a radial or spiral shape with respect to the center of the brush discharge surface.

In this way, in the cleaning treatment device, if the material of the brush body of the cleaning brush is fluororesin, the brush body can be prevented from being damaged and broken even when the cleaning liquid is especially ozone water, and brush cleaning is possible even under ozone water. For example, brush cleaning with HF and brush cleaning with ozone water can be performed alternately, and cleaning ability can be improved.

In addition, if the cross-sectional shape of the brush body is as described above, unlike the conventional brush body with a circular cross-sectional shape, the re-adhesion range due to insufficient cleaning liquid is prevented, and the brush body has substantially only a removal effect range. It can be done with Therefore, re-adhesion of foreign substances once removed can be suppressed.

Additionally, since the discharge pattern of the brush body is as described above, the cleaning liquid mixed under the cleaning brush can be drained smoothly. Therefore, retention of the cleaning liquid under the cleaning brush can be prevented, and re-adhesion of the removed foreign matter due to this retention can be suppressed.

Additionally, the plurality of brush bodies may be made of any one of PTFE, PCTFE, PVDF, PVF, PFA, FEP, ETFE, and ECTFE.

If it is made of such a material, it is possible to clean the brush under ozone water more reliably without damaging the brush body.

Additionally, the plurality of brush bodies may each be made of a bundle of hollow fibers or foam.

If this is the case, the ability to remove foreign substances can be further improved.

Additionally, the cleaning liquid may be any of pure water, SC1 liquid, hydrofluoric acid, and ozonated water.

In this way, as in the past, pure water or SC1 liquid can be used, and in addition, hydrofluoric acid or ozonated water can be used, and it is possible to further improve the cleaning ability.

Additionally, the wafer may be a polished silicon wafer.

In this way, the cleaning processing device of the present invention is particularly effective in cleaning processing of polished silicon wafers.

Additionally, each of the plurality of brush bodies may have the cross-sectional shape arranged in a horizontally longitudinal direction when the rotational direction of the rotatable brush head is vertical.

If this is the case, it can be made to have only the effective range of removing foreign substances more reliably, and re-adhesion of foreign substances can be suppressed more effectively.

As described above, the wafer cleaning method according to the first aspect of the present invention can prevent foreign substances from adhering to the wafer, and thus the number of defects on the wafer after cleaning can be reduced.

In addition, as described above, the cleaning device according to the second aspect of the present invention can improve the cleaning effect and suppress the occurrence of re-adhesion of removed foreign substances.

1 is a schematic flow diagram showing an example of a wafer cleaning method of the first aspect of the present invention.
Figure 2 is a schematic diagram showing an example of a cleaning treatment device of the 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 the rectangular cross-sectional shape of the 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 the heart-shaped cross-sectional shape of the brush body.
Fig. 8 is an explanatory diagram showing an example of the removal effect range in the case of a brush body with a semicircular cross-sectional shape.
Figure 9 is an explanatory diagram showing an example of a radial excretion pattern.
Figure 10 is an explanatory diagram showing an example of a swirl-like excretion pattern.
Fig. 11 is an explanatory diagram in plan view showing an example of the arrangement direction of the brush body with respect to the rotation direction (rotation direction) of the brush head when the cross-sectional shape of the brush body is rectangular.
Figure 12 is a schematic flowchart of a wafer cleaning method of a comparative example.
Figure 13 is a schematic flowchart of the wafer cleaning method of Examples 1 to 7.
Figure 14 is a graph showing the results of evaluating the number of wafer defects after cleaning in Comparative Examples and Examples 1 to 7.
Figure 15 is a schematic flowchart showing an example of a conventional wafer cleaning method.
Figure 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 the brush body in a conventional cleaning brush.
Fig. 18 is a schematic diagram showing another example of the shape of the brush body in a conventional cleaning brush.
Fig. 19 is an explanatory diagram showing an example of the positions of the effective range of removing foreign matter and the range of reattachment in the cylindrical brush body. The left side shows the position of the cleaning brush when viewed from the side, and the right side shows the position of the brush body in plan view.

<The First Sun>

As explained in [First Background], there has been a demand for the development of a wafer cleaning method that can reduce the number of defects on the wafer after brush cleaning.

The present inventor has carefully studied the above problem and found that adhesion of foreign substances such as silica occurs during HF treatment in brush cleaning. However, by adding an electrolyte to the HF solution, the zeta potential is controlled, and the foreign substances and the wafer are removed. It was discovered that adhesion could be suppressed by eliminating the absolute value difference in zeta potential. Additionally, it was discovered that by using a fluororesin brush in the brush treatment process, brush treatment was possible even during ozone water treatment, and HF treatment and ozone water treatment could be performed alternately. Based on this knowledge, the present inventor completed the first aspect of the present invention.

That is, the first aspect of the present invention is a method for cleaning a wafer subjected to a polishing process, comprising:

After the polishing process, an ozone water treatment process for treating the wafer with ozonated water;

After the ozone water treatment process, a brush cleaning process of brush cleaning the wafer using a fluorine resin brush.

Including,

The brush cleaning process includes a first brush cleaning process in which the wafer is brush cleaned using a solution containing HF and an electrolyte, and, after the first brush cleaning process, a second brush cleaning process in which the wafer is brush cleaned using ozonated water. A wafer cleaning method characterized by including processing.

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.

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

The wafer cleaning method of the first aspect of the present invention includes an ozone water treatment process performed on a wafer subjected to a polishing process and a subsequent brush cleaning process. The example shown in FIG. 1 further includes a final cleaning step of the brush cleaning step, but this step is an arbitrary step.

Hereinafter, each process will be described in detail.

(Polishing process)

The abrasive is not particularly limited, but for example, silica can be used. For example, by using silica particles with a primary particle size of 10 nm to 35 nm and a silica concentration of 0.01 mass% to 1.0 mass%, removal is possible by brush cleaning.

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

(Ozone water treatment process)

In the ozone water treatment process, after the polishing process, the wafer is treated with ozone water. In this ozone water treatment process, a wafer with an abrasive adhered to its entire surface immediately after polishing is treated with ozone water, for example, by brush cleaning or spin cleaning, thereby decomposing and removing the organic matter of the abrasive adhering to the wafer and forming an oxide film. there is.

The concentration of ozone water used in this ozone water treatment process is preferably 10 ppm or more and 50 ppm or less. It is desirable that the cleaning time be between 10 seconds and 60 seconds. When performing spin cleaning, it is desirable to set the rotation speed of the wafer to 5 rpm or more and 60 rpm or less. The ozone water flow rate in the ozone water treatment process is preferably 0.8 L/min or more and 4.0 L/min or less.

The ozone water treatment process is preferably performed under conditions where the oxide film thickness formed is 0.5 nm or more and 1.5 nm or less.

In the ozonated water treatment process, treatment with ozonated water may be performed once, but treatment may be performed multiple times.

(Brush cleaning process)

In the brush cleaning process, after the ozone water treatment process, the wafer is brush cleaned using a fluororesin brush. This brush cleaning process includes a first brush cleaning process of brush cleaning the wafer using a solution containing HF and electrolyte, and a second brush cleaning process of brush cleaning the wafer using ozonated water after the first brush cleaning process. do.

By using a fluorine resin brush, it becomes possible to perform brush cleaning even during the cleaning treatment using ozonated water, and the first brush cleaning treatment using HF and the second brush cleaning treatment using ozonated water can be performed alternately. Accordingly, in the wafer cleaning method of the first aspect of the present invention, the first and second brush cleaning processes can be repeatedly performed. By repeating the first and second brush cleaning processes, the number of defects on the wafer after cleaning can be further reduced.

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

Hereinafter, the first and second brush cleaning processes will be described in detail.

<First brush cleaning treatment>

In the first brush cleaning process, the wafer is brush cleaned using a solution containing HF and electrolyte.

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

By adding an electrolyte to the HF solution, the zeta potential can be controlled, making it possible to suppress adhesion of foreign substances to the wafer during the first brush cleaning process using HF. As a result, the number of defects on the wafer after cleaning can be reduced.

By using a solution with an electrolyte concentration of 0.05% by mass or more, adhesion of foreign substances in the first brush cleaning treatment can be more reliably suppressed.

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 brush cleaning treatment time is preferably set to a time that allows the treatment to remove the oxide film so that the bare surface is not exposed. For example, the cleaning time is preferably 5 seconds or more and 60 seconds or less. The HF flow rate is preferably set to, for example, 0.8 L/min or more and 4.0 L/min or less.

The rotation speed of the brush in the first brush cleaning treatment is not particularly limited, but can be, for example, 5 rpm or more and 200 rpm or less.

The first brush cleaning process can also be performed while rotating the wafer. The spin speed of the wafer in this case can be, for example, 5 rpm or more and 60 rpm or less. The direction of rotation of the wafer is not particularly limited. The direction of rotation of the brush is not particularly limited. For example, the spin direction of the wafer can be set to CCW (counterclockwise), and the rotation direction of the brush can be set to CW (clockwise). Alternatively, either direction may be clockwise or counterclockwise.

<Second brush cleaning treatment>

In the second brush cleaning process, the wafer is brush cleaned using ozonated water after the first brush cleaning process.

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

The ozone water concentration used in this second brush cleaning treatment is preferably 10 ppm or more and 50 ppm or less. It is desirable that the cleaning time be between 10 seconds and 180 seconds. When performing spin cleaning, it is desirable to set the rotation speed of the wafer to 5 or more and 60 rpm or less. The ozone water flow rate in the ozone water treatment process is preferably 0.8 L/min or more and 4.0 L/min or less.

The second brush cleaning treatment is preferably performed under conditions where the thickness of the oxide film formed is 0.5 nm or more and 1.5 nm or less.

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

The second brush cleaning process can also be performed while rotating the wafer. The spin speed of the wafer in this case can be, for example, 5 rpm or more and 60 rpm or less. The direction of rotation of the brush relative to the spin direction of the wafer is not particularly limited.

The first and second cleaning treatments can be performed repeatedly, as described above. The washing conditions for each time may be the same or may be different from each other.

(Final cleaning process)

The final cleaning process, which is an optional process in the first aspect of the present invention, is a process of spin cleaning or batch cleaning the wafer after the brush cleaning process.

In the final cleaning process, for example, cleaning with ozonated water, rinsing with pure water, cleaning with a chemical solution, cleaning with ozonated water, and rinsing with pure water can be performed in this order, but is not limited to this.

The concentration of ozone water used in each cleaning with ozone water can be, for example, 5 ppm or more and 40 ppm or less. The cleaning time with ozone water can be, for example, 10 seconds or more and 60 seconds or less. When cleaning with ozonated water is performed by spin cleaning, the rotation speed can be, for example, 5 rpm or more and 60 rpm or less. The ozone water flow rate can be, for example, 0.8 L/min or more and 4.0 L/min or less.

When each rinse with pure water is performed by spin cleaning, the spin speed of pure water can be, for example, 100 rpm or more and 1500 rpm or less. The pure water flow rate can be, for example, 0.8 L/min or more and 4.0 L/min or less. The pure rinse time can be, for example, 5 seconds or more and 60 seconds or less.

When cleaning with a chemical solution is performed by spin cleaning, the chemical solution spin speed can be, for example, 100 rpm or more and 1500 rpm or less. As a chemical solution, for example, HF, SC1 or SC2 can be used. The concentration of the chemical solution can be, for example, 0.1 mass% or more and 5.0 mass% or less. The flow rate of the chemical solution can be, for example, 0.8 L/min or more and 4.0 L/min or less. The cleaning time with the chemical solution can be, for example, 5 seconds or more and 60 seconds or less.

When using HF (hydrofluoric acid) as a chemical solution, the oxide film can be removed by, for example, hydrofluoric acid treatment by spin cleaning or batch cleaning after brush cleaning, and then the reoxidation film can be formed by ozone water treatment.

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

On the other hand, the wafer to be cleaned in the wafer cleaning method of the first aspect of the present invention is not particularly limited, but for example, a semiconductor silicon single crystal wafer can be the cleaning object.

<The Second Sun>

As described above in [Second Background], in the wafer cleaning and processing apparatus by brush cleaning using a cleaning brush, there were problems with low cleaning ability and re-adhesion of foreign substances. Accordingly, the present inventors conducted intensive research and found that the plurality of brush bodies in the cleaning brush are made of fluororesin and each has a cross-sectional shape one of semicircular, L-shaped, rectangular, triangular, and heart-shaped, It was discovered that brush cleaning in ozone water is possible, cleaning ability can be improved, and re-adhesion of foreign substances can be suppressed if the brush is excreted in a radial or spiral shape with respect to the center of the brush discharge surface, and the present invention The second sun was completed.

Hereinafter, embodiments 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.

Figure 2 shows an example of a cleaning treatment device according to the second aspect of the present invention. The cleaning treatment device (1) is a single wafer type device and is equipped with a cleaning liquid supply mechanism (2) and a cleaning brush (3). Additionally, it is provided with a wafer holder 4 that holds the wafer W to be cleaned.

The wafer to be cleaned by the cleaning device 1 of the second aspect of the present invention is not particularly limited, and may include various semiconductor wafers such as semiconductor silicon wafers and compound semiconductor wafers, and in particular, polished silicon wafers. . In addition, the device can clean various types of wafers such as glass substrates.

The wafer holder 4 can rotate by a drive source (not shown), and the held wafer W can rotate due to its rotation. For example, the same thing as before can be used.

Additionally, the cleaning liquid supply mechanism 2 can be, for example, a nozzle as shown in Fig. 2. This nozzle supplies the cleaning liquid to the surface to be cleaned (S) of the wafer (W) held in the wafer holder (4). Examples of cleaning liquids include pure water and SC1 liquid, which have conventionally been generally used for cleaning. Furthermore, it is also possible to supply HF or ozonated water. As will be described later, the cleaning brush 3 in the second aspect of the present invention is particularly resistant to ozonated water, and in order to improve the cleaning ability and reform the oxide film, HF and ozonated water may be supplied alternately when cleaning the brush. there is.

Meanwhile, an example of a nozzle has been described as the cleaning liquid supply mechanism 2, but it can also be integrated with the cleaning brush 3 and can be configured to discharge the cleaning liquid from the lower center of the cleaning brush 3.

The cleaning brush 3 is located above the wafer W and is opposed to the surface S of the wafer W to be cleaned. It is provided with a brush head (5) having a brush discharge surface (B) facing the surface to be cleaned (S), and a plurality of brush bodies (6) disposed on the brush discharge surface (B). Then, the brush body 6 is brought into contact with the surface to be cleaned S to perform brush cleaning.

The brush head 5 can rotate by a drive source (not shown), and when the brush head 5 rotates, the brush body 6 fixed to the brush discharge surface B rotates together.

Additionally, the material of the brush body 6 is fluororesin. The conventional brush body made of PVA had the possibility of being damaged and broken under ozone water. However, the brush body 6 made of fluororesin as in the second aspect of the present invention is resistant to ozonated water and does not suffer damage or breakage like conventional products. Therefore, it is also possible to perform brush cleaning using HF and ozone water alternately. In this case, in order to be able to more reliably clean the brush under ozone water without damaging the brush body 6, the brush can be selected from, for example, PTFE, PCTFE, PVDF, PVF, PFA, FEP, ETFE, ECTFE, etc.

Additionally, compared to those originally made of PVA, those made of fluorine resin have a higher cleaning ability.

Additionally, each of these brush bodies 6 may be made of, for example, a bundle of hollow fibers. The number per bundle is not particularly limited, but can range from dozens to hundreds, for example. Additionally, foam may be used instead of a bundle of hollow fibers. With something like these, the ability to remove foreign substances can be further improved.

Additionally, the shape of the brush body 6 also has characteristics. Conventional devices have a cylindrical shape, that is, a circular cross-sectional shape. However, the brush body 6 in the second aspect of the present invention has a cross-sectional shape that is one of semicircular, L-shaped, rectangular, triangular, and heart-shaped. It is. Examples of these shapes are shown in Figures 3-7.

Here, in the case where the cross-sectional shape is circular as in the past, as shown in FIG. 19, foreign matter can be removed from the front side relative to the rotation direction of the rotating brush head (removal effect range), but the cleaning liquid becomes insufficient at the rear side, There was a re-adhesion range where the removed foreign matter re-adhered.

On the other hand, in the case of the second aspect of the present invention, since it is not circular but semicircular, etc., as shown in FIG. 8, it has a shape that substantially only has a removal effect range, and the occurrence of a reattachment range can be suppressed. Therefore, it is possible to suppress re-attachment of foreign substances once removed, which is a problem in conventional cleaning devices.

Meanwhile, in Figure 8, an example is shown in the case of a semicircular shape, but other shapes (L-shaped, rectangular, triangular, heart-shaped) also have only a removal effect range.

A plurality of brush bodies 6 as described above are disposed side by side on the brush discharge surface B of the brush head 5, but the discharge pattern is radial or spiral with respect to the center of the brush discharge surface B. there is. Figure 9 shows the radial excretion pattern, and Figure 10 shows the swirl-shaped excretion pattern (upper left corner, respectively). Meanwhile, an example in which the cross-sectional shape of the brush body 6 is as shown in Fig. 3-7 is also shown.

By using a radial or swirl-like discharge pattern, the cleaning liquid mixed between the cleaning brush 3 (brush head 5) and the wafer W during cleaning can be efficiently drained. That is, foreign substances removed through brush cleaning using the cleaning brush 3 can also be smoothly discharged along with the cleaning liquid. Therefore, retention of the cleaning liquid between the cleaning brush and the wafer W can be prevented. Therefore, it is possible to prevent the removed foreign matter from re-adhering due to retention of the cleaning liquid.

On the other hand, the number of brush bodies 6 disposed on the brush installation surface B may be plural, and the number is not particularly limited. It can be appropriately determined based on the size of the brush discharge surface B, the size of each brush body 6, the type of wafer W to be cleaned, the type of cleaning liquid, etc.

In addition, there is no particular limitation on the method of disposing the brush body 6 to the brush installation surface B, but in particular, the cross section of the brush body 6 with respect to the rotation direction (rotation direction) of the brush head 5. It is preferable that the shape is arranged in a horizontally long direction. Here, as an example, when the cross-sectional shape of the brush body 6 is rectangular, the arrangement direction of the brush body 6 with respect to the rotation direction (rotation direction) of the brush head 5 is shown in Fig. 11. As shown in the plan view of Fig. 11, when the rotation direction of the brush head 5 is vertical (upward direction in the drawing), the long side of the rectangular shape (cross-sectional shape) is in the horizontal direction (left and right directions in the drawing). , the cross-sectional shape as a whole is such that the brush body 6 is disposed in the horizontal longitudinal direction. On the other hand, an example has been shown where the long side intersects perpendicularly with respect to the rotation direction of the brush head 5, but of course it can also be angled at an angle. In the case of other cross-sectional shapes as well, each brush body 6 can be disposed in the horizontal longitudinal direction. By excreting in this direction, it is possible to more reliably have only a removal effect range and no reattachment range, and reattachment of foreign substances can be suppressed more effectively.

An example of a cleaning process including brush cleaning of a wafer using the cleaning apparatus 1 of the second aspect of the present invention as described above will be described.

First, for example, a wafer W (silicon wafer, etc.) is prepared that has been subjected to polishing treatment and then subjected to ozone water treatment to decompose and remove organic substances from the abrasive adhering to the surface and form an oxide film, and then use a cleaning treatment device (1). ) is maintained with the wafer holder (4).

While HF is supplied as a cleaning liquid to the surface S to be cleaned from a nozzle that is the cleaning liquid supply mechanism 2, the brush body 6 of the cleaning brush 3 is brought into contact with the surface S to be cleaned to perform brush cleaning. At this time, the entire cleaning surface S is brush cleaned by rotating the cleaning brush 3 and moving it in parallel on the wafer W.

The concentration of HF to be supplied can be, for example, 1.0% by mass or less, but is not particularly limited.

It is preferable that the cleaning treatment time is such that the oxide film can be removed so that the bare surface is not exposed. For example, it can be more than 5 seconds and less than 60 seconds.

The HF flow rate can be, for example, 0.8 L/min or more and 4.0 L/min or less.

The rotation speed of the cleaning brush 3 is not particularly limited, but can be, for example, 5 rpm or more and 200 rpm or less.

Meanwhile, during this brush cleaning, the wafer W itself may be rotated, but does not need to be rotated. When rotating, the spin speed of the wafer W can be, for example, 5 rpm or more and 60 rpm or less. The direction of rotation of the wafer W is not particularly limited. The rotation direction of the cleaning brush 3 is not particularly limited. For example, the spin direction of the wafer W can be set to CCW (counterclockwise), and the rotation direction of the cleaning brush 3 can be set to CW (clockwise). Alternatively, either direction may be clockwise or counterclockwise.

Next, brush cleaning is performed by supplying ozonated water instead of HF.

The concentration of ozone water supplied can be, for example, 10 ppm or more and 50 ppm or less.

The cleaning time can be, for example, 10 seconds or more and 180 seconds or less.

The ozone water flow rate can be 0.8 L/min or more and 4.0 L/min or less.

The rotation speed of the cleaning brush 3 is not particularly limited, but can be, for example, 5 rpm or more and 200 rpm or less.

Rotation of the wafer W itself can be done in the same manner as, for example, the brush cleaning with HF described above.

It is desirable to carry out this process under conditions where the oxide film thickness formed in this process is 0.8 nm or more and 1.5 nm or less.

This brush cleaning with HF and brush cleaning with ozone water can be repeated alternately as needed. The washing conditions for each session may be the same or may be different from each other.

On the other hand, brush cleaning may be performed using pure water or SC1 liquid at an appropriate timing as needed. After brush cleaning is performed using the cleaning apparatus 1 of the second aspect of the present invention as described above, spin cleaning or batch cleaning, for example, can be performed as final cleaning. During these cleanings, in particular, HF can be used to remove the oxide film, and then ozone water can be used to form the reoxidation film.

By the above cleaning process, foreign substances are efficiently removed, their re-adhesion is suppressed, and a wafer W with high cleanliness can be obtained.

[Example]

Hereinafter, the first aspect of the present invention will be specifically described using examples and comparative examples, but the first aspect of the present invention is not limited to these.

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

(Comparative example)

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

Next, the wafer with the polished abrasive adhered was treated with ozone water in an ozone water treatment process. The ozonated water treatment involved spin cleaning using ozonated water, followed by brush cleaning using ozonated water. The conditions of the ozone water treatment process are shown in Table 2 below.

Next, the wafer was brush cleaned using an HF solution (brush cleaning treatment (HF)). The brush cleaning treatment (HF) was performed while rotating the brush and the wafer. The conditions of the brush cleaning treatment (HF) are shown in Table 3 below.

Next, the wafer was brush cleaned using ozonated water (brush cleaning treatment (ozonated water)). The brush cleaning treatment (ozone water) was performed while rotating the brush and wafer. The conditions of the brush cleaning treatment (ozone water) are shown in Table 4 below.

The brush cleaning treatment (HF) and the subsequent brush cleaning treatment (ozone water) described above were repeated three times under the conditions shown in Tables 3 and 4, respectively, and then spin cleaning was performed as a final cleaning.

In the spin cleaning, spin cleaning using ozonated water, rinsing with pure water, spin cleaning using a chemical solution, spin cleaning using ozonated water, and rinsing with pure water were performed in this order. Next, the wafer after spin cleaning was dried. The conditions for spin cleaning and drying are summarized in Table 5 below.

(Examples 1 to 7)

In Examples 1 to 7, wafers were cleaned according to the cleaning flow shown in FIG. 13. Specifically, in Examples 1 to 7, after the ozone water treatment process, a brush cleaning treatment using a solution containing HF and NaCl instead of the brush cleaning treatment (HF) performed in the comparative example (first brush cleaning treatment (HF + NaCl) )), and then the same brush cleaning treatment (second brush cleaning treatment (ozonated water)) as the brush cleaning treatment (ozonated water) of the comparative example, except that the first and second brush cleaning treatments were repeated three times. The wafer was cleaned under the same conditions as in the comparative example.

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

(evaluation)

Figure 14 shows the results of evaluating the number of wafer defects after cleaning in Comparative Examples and Examples 1 to 7.

As is clear from FIG. 14, in Examples 1 to 7, the number of defects on the wafer after cleaning was reduced and the number of defects was improved compared to the comparative example.

In the comparative example, since no electrolyte was added to the HF solution used in the brush cleaning treatment (HF), it is believed that foreign substances re-attached to the wafer during this treatment, increasing the number of defects.

Additionally, in Examples 1 to 7, since a fluororesin-based brush was used for brush cleaning, brush cleaning could be performed without problems even during ozone water treatment.

Meanwhile, the present invention is not limited to the above embodiments. The above-mentioned embodiment is an example, and anything that has substantially the same structure as the technical idea described in the claims of the present invention and exhibits the same operation and effect is included in the technical scope of the present invention.

Claims (11)

A method of cleaning a wafer subjected to a polishing process, comprising:
After the polishing process, an ozone water treatment process for treating the wafer with ozonated water;
After the ozone water treatment process, a brush cleaning process of brush cleaning the wafer using a fluorine resin brush.
Including,
The brush cleaning process includes a first brush cleaning process in which the wafer is brush cleaned using a solution containing HF and an electrolyte, and, after the first brush cleaning process, a second brush cleaning process in which the wafer is brush cleaned using ozonated water. A wafer cleaning method comprising processing.
According to paragraph 1,
In the brush cleaning process, the wafer cleaning method is characterized in that the first and second brush cleaning processes are repeatedly performed.
According to claim 1 or 2,
In the ozone water treatment process, the wafer subjected to the polishing process is brush cleaned or spin cleaned using ozonated water.
According to any one of claims 1 to 3,
After the brush cleaning process, a wafer cleaning method further comprising a final cleaning process of spin cleaning or batch cleaning the wafer.
According to any one of claims 1 to 4,
A wafer cleaning method characterized in that, in the first brush cleaning treatment, the solution having a concentration of the electrolyte of 0.05% by mass or more is used.
A cleaning processing device comprising a cleaning liquid supply mechanism for supplying a cleaning liquid to a surface to be cleaned of a wafer, and a rotatable cleaning brush disposed opposite to the surface to be cleaned and brush cleaning the surface to be cleaned, comprising:
The cleaning brush has a rotatable brush head and a plurality of brush bodies disposed on a brush discharge surface of the brush head that faces the surface to be cleaned of the wafer,
The plurality of brush bodies are,
The material is fluororesin,
Each cross-sectional shape is one of semicircular, L-shaped, rectangular, triangular, and heart-shaped,
A cleaning treatment device characterized in that the discharge is arranged in a radial or spiral shape with respect to the center of the brush discharge surface.
According to clause 6,
A cleaning device, characterized in that the plurality of brush bodies are made of any one of PTFE, PCTFE, PVDF, PVF, PFA, FEP, ETFE, and ECTFE.
According to clause 6 or 7,
A cleaning treatment device, wherein the plurality of brush bodies are each a bundle of hollow fibers or a foam body.
According to any one of claims 6 to 8,
A cleaning treatment device, characterized in that the cleaning liquid is any one of pure water, SC1 liquid, hydrofluoric acid, and ozonated water.
According to any one of claims 6 to 9,
A cleaning processing device, wherein the wafer is a polished silicon wafer.
According to any one of claims 6 to 10,
A cleaning treatment device, wherein each of the plurality of brush bodies has a cross-sectional shape arranged in a horizontally longitudinal direction when the rotation direction of the rotatable brush head is vertical.