JP7578063B2 - Cleaning Equipment - Google Patents

Description

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

During the manufacturing process of semiconductor wafers and the like, brush cleaning is performed using cleaning brushes to remove foreign matter 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 use a cleaning treatment device to perform brush cleaning with pure water or SC1 liquid.

As shown in FIG. 11, this conventional cleaning processing apparatus 101 includes a cleaning liquid supply mechanism 102 that supplies the above-mentioned cleaning liquid to the surface to be cleaned of the wafer W, and a cleaning brush 103 that is arranged opposite the surface to be cleaned of the wafer W and brush-cleans the surface to be cleaned.
The cleaning brush 103 has a brush head 105 and a brush body 106 fixedly disposed on the brush head 105. Above the wafer W, the brush head 105 rotates (rotates on its axis) and can also move in parallel to the left or right in any direction.

Examples of brush bodies in conventional cleaning brushes are shown in Figures 12 and 13. In some cases, only one brush body is provided for the brush head as in Figure 12, and in other cases, multiple brush bodies are provided as in Figure 13, but the shape of the brush body is generally cylindrical. In other words, the cross-sectional shape of the brush body is circular.
The material of the brush body is generally PVA.

When the surface of the wafer to be cleaned is brush-cleaned, the wafer is rotated and cleaning liquid is supplied onto the wafer while the rotating brush head is moved to bring the brush body of the cleaning brush into contact with the wafer, thereby removing any foreign matter adhering to the wafer. Cleaning is performed while moving the wafer and the brush head so that the brush body of the cleaning brush comes into contact with and brush-cleans the entire surface of the wafer to be cleaned.

Japanese Patent Application Publication No. 10-92780

When using the above-mentioned conventional cleaning processing equipment to perform brush cleaning using hydrofluoric acid (HF) or ozone water to improve the cleaning capacity, ozone water treatment is required to re-form the oxide film after HF treatment. If the brush body of the cleaning brush is made of PVA, there is a possibility that the brush body will be damaged by the ozone water and broken.
Another problem is that the PVA brush body has low cleaning ability (ability to remove foreign matter).

In addition, as mentioned above, conventional cleaning brushes have one brush body and no arrangement pattern on the brush head, or even if there are multiple brush bodies, they are cylindrical (with a circular cross-sectional shape). In these cases, there is a problem that the foreign matter removed by the brush body is not smoothly removed from the wafer and reattaches to the wafer.
14 is an explanatory diagram showing the position of the range where the removed foreign matter can be removed (removal effective range) and the range where the removed foreign matter re-attaches (reattachment range) in the cylindrical brush body of the cleaning brush. The cleaning effect (foreign matter removal effect) is only present near the front edge in the moving direction (rotation direction of the brush head), and in the case of no pattern or a cylindrical brush body, the lack of cleaning liquid on the rear side of the brush body causes foreign matter to re-attach to the wafer.

Furthermore, if the brush body arrangement pattern is not appropriate, the cleaning liquid cannot be drained efficiently and accumulates around the brush body, which also creates the problem of removed foreign matter re-adhering to the wafer.

The present invention has been made in consideration of the above problems, and aims to provide a cleaning processing device that has a high cleaning effect and can prevent reattachment of foreign matter once removed.

In order to achieve the above object, the present invention provides a cleaning processing apparatus including 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 the surface to be cleaned and for brush-cleaning the surface to be cleaned,
The cleaning brush has a rotatable brush head and a plurality of brush bodies arranged on a brush arrangement 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 a semicircular shape, an L-shape, a rectangular shape, a triangular shape, and a heart shape;
The cleaning device is characterized in that the brushes are arranged radially or spirally about the center of the brush arrangement surface.

In this manner, in a cleaning processing 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, in particular, ozone water, making it possible to perform brush cleaning even in ozone water. For example, brush cleaning with HF and brush cleaning with ozone water can be performed alternately, thereby improving the cleaning ability.
Furthermore, unlike conventional brush bodies having a circular cross section, the cross-sectional shape of the brush body as described above can prevent the occurrence of areas of re-adhesion due to a lack of cleaning liquid, and can substantially limit the area of effective removal, thereby preventing re-adhesion of foreign matter once removed.
In addition, because the brush body is arranged in the above-described pattern, the cleaning liquid taken under the cleaning brush can be smoothly drained, which prevents the cleaning liquid from accumulating under the cleaning brush and inhibits the removed foreign matter from re-adhering due to the accumulating liquid.

The multiple brush bodies may be made of any one of the following materials: PTFE, PCTFE, PVDF, PVF, PFA, FEP, ETFE, and ECTFE.

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

Additionally, each of the multiple brush bodies can be a bundle of hollow fibers or a foam.

Such a device would be able to further improve the ability to remove foreign matter.

The cleaning liquid can be any of the following: pure water, SC1 liquid, hydrofluoric acid, and ozone water.

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

The wafer may also be a polished silicon wafer.

As such, the cleaning processing device of the present invention is particularly effective for cleaning polished silicon wafers.

Furthermore, each of the multiple brush bodies can be arranged so that the cross-sectional shape is horizontal when the rotation direction of the rotatable brush head is vertical.

In this way, it is possible to more reliably achieve a range that is effective in removing foreign matter, and to more effectively prevent the re-adhesion of foreign matter.

As described above, the cleaning processing device of the present invention can improve the cleaning effect and prevent the reattachment of removed foreign matter.

1 is a schematic diagram showing an example of a cleaning treatment apparatus of the present invention. FIG. 4 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 an L-shaped cross-sectional shape of a brush body. FIG. 4 is an explanatory diagram showing an example of a rectangular cross-sectional shape of the brush body. 4 is an explanatory diagram showing an example of a triangular cross-sectional shape of the brush body; FIG. FIG. 4 is an explanatory diagram showing an example of a heart-shaped cross-sectional shape of a brush body. FIG. 11 is an explanatory diagram showing an example of a removal effect range in the case of a brush body having a semicircular cross-sectional shape; FIG. 13 is an explanatory diagram showing an example of a radial arrangement pattern. FIG. 13 is an explanatory diagram showing an example of a spiral arrangement pattern. 1 is an explanatory diagram in a plan view showing an example of the orientation of a brush body relative to the rotation direction (rotation direction) of a brush head when the cross-sectional shape of the brush body is rectangular. FIG. FIG. 1 is a schematic diagram showing an example of a conventional cleaning treatment apparatus. FIG. 1 is a schematic diagram showing an example of the shape of a brush body in a conventional cleaning brush. FIG. 11 is a schematic diagram showing another example of the shape of a brush body in a conventional cleaning brush. 1 is an explanatory diagram showing an example of the positions of the foreign matter removal effect range and the re-adhesion range in a cylindrical brush body, the left side showing the positions when the cleaning brush is viewed from the side, and the right side showing the positions in a plan view of the brush body.

As mentioned above, problems existed with low cleaning performance and foreign matter reattachment in wafer cleaning processing equipment using cleaning brushes. The inventors conducted extensive research and discovered that if the multiple brush bodies in the cleaning brush are made of fluororesin, each of which has a cross-sectional shape that is either semicircular, L-shaped, rectangular, triangular, or heart-shaped, and are arranged radially or spirally around the center of the brush arrangement surface, brush cleaning can be performed under ozone water, cleaning performance can be improved, and foreign matter reattachment can be suppressed, leading to the completion of the present invention.

Hereinafter, the present invention will be described with reference to the drawings. However, the present invention is not limited to the embodiments.
An example of the cleaning processing apparatus of the present invention is shown in Fig. 1. The cleaning processing apparatus 1 is a single-wafer processing apparatus, and includes a cleaning liquid supply mechanism 2 and a cleaning brush 3. It also includes a wafer holder 4 for holding a wafer W to be cleaned.

The wafers to be cleaned by the cleaning processing device 1 of the present invention are not particularly limited, and examples include various semiconductor wafers such as semiconductor silicon wafers and compound semiconductor wafers, and in particular polished silicon wafers. In addition, the device can also clean various wafer-like objects such as glass substrates.

The wafer holder 4 can be rotated by a drive source (not shown), and the rotation of the wafer holder 4 can rotate the held wafer W. For example, a conventional one can be used.
The cleaning liquid supply mechanism 2 may be, for example, a nozzle as shown in FIG. 1. This nozzle supplies the 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, which have been conventionally used in cleaning. Furthermore, HF and ozone water can also be supplied. As will be described later, the cleaning brush 3 in the present invention is particularly resistant to ozone water, and HF and ozone water can be supplied alternately during brush cleaning in order to improve the cleaning ability and re-form the oxide film.
Although the example of the nozzle as the cleaning liquid supply mechanism 2 has been described, it may also be configured such that it is integrated with the cleaning brush 3 and the cleaning liquid can be discharged from the central lower part of the cleaning brush 3.

The cleaning brush 3 is positioned above the wafer W and faces the surface S of the wafer W to be cleaned. It is equipped with a brush head 5 having a brush arrangement surface B facing the surface S to be cleaned, and a number of brush bodies 6 arranged on the brush arrangement surface B. These brush bodies 6 are brought into contact with the surface S to be cleaned to perform brush cleaning.

The brush head 5 can rotate on its axis due to a drive source (not shown), and as the brush head 5 rotates on its axis, the brush body 6 fixedly arranged on the brush arrangement surface B also rotates.

The brush body 6 is made of fluororesin. Conventional brush bodies made of PVA may be damaged and broken under ozone water. However, the brush body 6 made of fluororesin according to the present invention is resistant to ozone water and will not break due to damage as in the conventional brush body. Therefore, it is possible to perform brush cleaning using HF and ozone water alternately. In this case, the material can be selected from, for example, PTFE, PCTFE, PVDF, PVF, PFA, FEP, ETFE, ECTFE, etc., so that brush cleaning can be performed more reliably under ozone water without damaging the brush body 6.
In addition, fluororesin cleaners have a higher cleaning ability than PVA cleaners.

The brush body 6 can be made of, for example, a bundle of hollow fibers. There is no particular limit to the number of fibers in each bundle, but it can be, for example, several tens to several hundreds. Also, foam can be used instead of bundles of hollow fibers. These types of materials can further improve the ability to remove foreign matter.

The shape of the brush body 6 is also characteristic. Conventional brush bodies are cylindrical, i.e., the cross section is circular, but the brush body 6 of the present invention has a cross section that is semicircular, L-shaped, rectangular, triangular, or heart-shaped. Examples of these shapes are shown in Figures 2-6.
Here, in the case of a conventional brush with a circular cross-sectional shape, as shown in Figure 14, foreign matter can be removed at the front side in the direction of rotation of the rotating brush head (effective removal range), but due to a shortage of cleaning liquid at the rear side, a re-adhesion range is created where the removed foreign matter re-adheres.
On the other hand, in the case of the present invention, since the shape is not circular but semicircular, as shown in Fig. 7, the shape has only the effective removal range, and the occurrence of the re-adhesion range can be suppressed. Therefore, it is possible to suppress the re-adhesion of the foreign matter once removed, which is a problem in the conventional cleaning apparatus.
Although FIG. 7 shows an example in which the shape is semicircular, other shapes (L-shape, rectangle, triangle, heart shape) also have the same removal effect range.

A plurality of brush bodies 6 as described above are arranged side by side on the brush arrangement surface B of the brush head 5, and the arrangement pattern is radial or spiral with respect to the center of the brush arrangement surface B. Figure 8 shows a radial arrangement pattern, and Figure 9 shows a spiral arrangement pattern (top left corners of each). An example in which the brush bodies 6 have the cross-sectional shape shown in Figure 2-6 are arranged is also shown.
The radial or spiral arrangement pattern allows efficient drainage of the cleaning liquid trapped between the cleaning brush 3 (brush head 5) and the wafer W during cleaning. That is, foreign matter removed by brush cleaning using the cleaning brush 3 can be smoothly discharged together with the cleaning liquid. This makes it possible to prevent the cleaning liquid from stagnation between the cleaning brush and the wafer W. This makes it possible to prevent the removed foreign matter from re-adhering due to the stagnation of the cleaning liquid.

The number of brush bodies 6 arranged on the brush arrangement surface B is not particularly limited as long as there is more than one. The number can be determined appropriately depending on the size of the brush arrangement 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, the manner in which the brush body 6 is arranged on the brush arrangement surface B is not particularly limited, but it is particularly preferable that the brush body 6 is arranged in such a way that the cross-sectional shape of the brush body 6 is horizontally long relative to the rotation direction (rotation direction) of the brush head 5. Here, as an example, FIG. 10 shows the arrangement direction of the brush body 6 with respect to the rotation direction (rotation 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. 10, when the rotation direction of the brush head 5 is the vertical direction (upward in the drawing), the brush body 6 is arranged in such a way that the cross-sectional shape is horizontal as a whole so that the long side of the rectangle (cross-sectional shape) is horizontal (left and right in the drawing). Note that, although an example is shown in which the long side is arranged perpendicular to the rotation direction of the brush head 5, it may of course be tilted by shifting the angle. In the case of other cross-sectional shapes, each brush body 6 can be arranged in such a way that it is horizontally long in the same manner. Arranging it in this way will more reliably provide only a removal effect range and no reattachment range, further effectively preventing reattachment of foreign matter.

An example of a cleaning process including brush cleaning of a wafer using the cleaning processing apparatus 1 of the present invention as described above will be described.
First, for example, a wafer W (such as a silicon wafer) is prepared which has been subjected to a polishing process, and then an ozone water process is used to decompose and remove organic matter from the abrasive adhering to the surface and form an oxide film thereon, and the wafer is held by the wafer holder 4 of the cleaning processing device 1.

While HF is supplied as a cleaning liquid from a nozzle that is a cleaning liquid supply mechanism 2 to the surface S to be cleaned, the brush body 6 of the cleaning brush 3 is brought into contact with the surface S to be cleaned for brush cleaning. At this time, the cleaning brush 3 is rotated on its axis and translated on the wafer W to brush-clean the entire surface S to be cleaned.
The concentration of HF supplied can be, for example, 1.0 mass % or less, but is not particularly limited.
The cleaning process time is preferably set to a time that allows the oxide film to be removed without exposing a bare surface, and may be set to, for example, 5 to 60 seconds.
The HF flow rate can be, for example, 0.8 L/min to 4.0 L/min.
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.

During this brush cleaning, the wafer W itself may or may not be rotated. If rotated, the spin speed of the wafer W may be, for example, 5 rpm or more and 60 rpm or less. 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 spin direction of the wafer W may be CCW (counterclockwise), and the rotation direction of the cleaning brush 3 may be CW (clockwise). Alternatively, both may be clockwise or counterclockwise.

Next, ozone water is supplied instead of HF to perform brush cleaning.
The concentration of the ozone water to be supplied may be, for example, 10 ppm or more and 50 ppm or less.
The cleaning time can be, for example, from 10 seconds to 180 seconds.
The flow rate of the ozone water may be set to 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.
The rotation of the wafer W itself can be the same as that in the brush cleaning with HF described above.
It is preferable to carry out this process under conditions in which the thickness of the oxide film formed is 0.8 nm to 1.5 nm.

Such brush cleaning with HF and brush cleaning with ozone water can be repeated alternately as necessary. The cleaning conditions for each step may be the same or different.

If necessary, brush cleaning may be performed at an appropriate timing using pure water or SC1 liquid. After performing brush cleaning using the cleaning processing device 1 of the present invention as described above, for example, spin cleaning or batch cleaning can be performed as a finishing cleaning. During these cleaning operations, in particular, after removing the oxide film using HF, a re-oxide film can be formed using ozone water.

By carrying out the above-described cleaning process, foreign matter is efficiently removed and its re-adhesion is suppressed, resulting in a wafer W with a high level of cleanliness.

The present invention is not limited to the above-described embodiments. The above-described embodiments are merely examples, and anything that has substantially the same configuration as the technical idea described in the claims of the present invention and exhibits similar effects is included within the technical scope of the present invention.

1... cleaning treatment device of the present invention, 2... cleaning liquid supply mechanism, 3... cleaning brush,
4...wafer holder, 5...brush head, 6...brush body,
B: brush-mounted surface; S: surface to be cleaned; W: wafer.

Claims (6)

A cleaning processing apparatus 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 the surface to be cleaned and for brush-cleaning the surface to be cleaned,
The cleaning brush has a rotatable brush head and a plurality of brush bodies arranged on a brush arrangement 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 a semicircular shape, an L-shape , a triangular shape , and a heart shape;
3. A cleaning treatment device, comprising: brushes arranged radially or spirally about the center of said brush arrangement surface. The cleaning processing device according to claim 1, characterized in that the plurality of brush bodies are made of any one of the following materials: PTFE, PCTFE, PVDF, PVF, PFA, FEP, ETFE, and ECTFE. The cleaning treatment device according to claim 1 or 2, characterized in that each of the multiple brush bodies is a bundle of hollow fibers or a foam body. The cleaning processing apparatus according to any one of claims 1 to 3, characterized in that the cleaning liquid is any one of pure water, SC1 liquid, hydrofluoric acid, and ozone water. The cleaning processing apparatus according to any one of claims 1 to 4, characterized in that the wafer is a polished silicon wafer. The cleaning processing device according to any one of claims 1 to 5, characterized in that the plurality of brush bodies are each arranged in such a way that, when the rotation direction of the rotatable brush head is the vertical direction, the cross-sectional shape is horizontal.

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