JP7529481B2 - Single wafer cleaning equipment - Google Patents

Description

The present invention relates to a single-wafer cleaning apparatus for cleaning substrates.

In conventional single-wafer cleaning equipment that rotates and cleans substrates, a cylindrical cup is commonly installed around the substrate to block the cleaning liquid that splashes from the substrate during the cleaning and drying processes (see, for example, Patent Document 1). In addition, an exhaust duct is installed around the substrate in the cup to create a downflow air current.

8 shows a top view and a vertical cross-sectional view of an example of such a conventional single wafer cleaning apparatus. The top view is shown on the upper side, and the bottom view is shown on the vertical cross-sectional view. The single wafer cleaning apparatus 101 has a table base 103 on a bottom plate 102 of a processing chamber where cleaning is performed, and a turntable 105 on which a substrate W to be cleaned is held and rotated by substrate holding pins 104. The apparatus also has a rotation motor 106 for rotating the turntable 105.
A back surface cleaning nozzle 107 that supplies cleaning liquid toward the back surface of the substrate W is installed on the turntable 105, and a front surface cleaning nozzle 108 that supplies cleaning liquid toward the front surface of the substrate W is installed above the substrate W. The front surface cleaning nozzle 108 is connected to an arm shaft 110 via a swivel arm 109, and as the arm shaft 110 rotates and the swivel arm 109 swivels, the front surface cleaning nozzle 108 swivels within the cup and can be moved outside the cup when on standby.

A cylindrical cup 111 is provided around the substrate W so as to surround the turntable 105. An exhaust duct 112 for forming a downflow air current around the substrate W is provided on the bottom plate 102 inside the cup 111.
When such a single-wafer cleaning apparatus 101 is used to clean and dry a substrate W, the cleaning liquid scattered from the substrate W is blocked by the cup 111 and becomes a fine mist that bounces back in the direction of the substrate W. This mist is suppressed by a downflow air current formed by the exhaust duct 112, preventing it from reaching the substrate W.

In this case, the exhaust ducts 112 are installed around the rotary motor 106, but since installing a large number of exhaust ducts 112 would make it impossible to access the rotary motor 106, only two exhaust ducts 112 are installed in the cup 111, and they are placed on opposite sides of the rotary table 105, taking into consideration ease of maintenance. However, in this case, although a downflow is established near the exhaust ducts 112 in the cup 111, for example, at a position 90° away from the exhaust duct 112 in the circumferential direction, the exhaust effect tends to be weakened and the downflow tends to be extremely weak.

JP 2007-294490 A

When the substrate W rotates at high speed for cleaning and drying, droplets of the cleaning liquid are sprayed evenly over 360° into the cup 111, and due to interference with the cup 111, they become a fine mist and bounce back towards the substrate W. In positions where the downflow is weak as described above, the bouncing mist cannot be controlled and reaches the substrate W, causing quality defects such as being detected as water stains (watermarks) on the substrate or attaching foreign matter or metal components that were attached to the cup 111 itself.

The present invention aims to provide a single-wafer cleaning apparatus that spin-cleans and spin-dries substrates and that can prevent mist caused by rebounding cleaning liquid from reaching the substrate.

In order to achieve the above object, the present invention provides a bottom plate,
a rotary table that is disposed on the bottom plate and that supports and rotates a substrate to be cleaned;
a cleaning nozzle for supplying a cleaning liquid to the substrate;
a cylindrical cup disposed on the bottom plate so as to surround the turntable and configured to prevent the cleaning liquid supplied to the substrate from scattering;
an exhaust duct disposed on the bottom plate at a position inside the cup and forming a downflow air current around the substrate,
a cylindrical permeable plate that is disposed inside the cup, has a through hole from the substrate side to the cup side, and allows the cleaning liquid splashed from the substrate to pass through the through hole to the cup side, and prevents the cleaning liquid that has passed through the cup side and rebounded from the cup from reaching the substrate;
an exhaust dispersion plate, which is a raised bottom disposed above the bottom plate and inside the cup, has a plurality of exhaust ports from the substrate side to the exhaust duct side, and through which the downflow airflow around the substrate flows into the exhaust duct through the exhaust ports; or

In the single-wafer cleaning apparatus of the present invention, by providing a permeable plate with through holes on the inside of the cup, it is possible to prevent mist of cleaning liquid that passes through the through holes into the cup and bounces back from reaching the substrate. In addition, by providing an exhaust dispersion plate with multiple exhaust ports above the bottom plate, the downflow airflow around the substrate is made uniform, and the present invention can prevent mist from reaching the substrate even in positions where the downflow is weak in conventional apparatus. As a result, it is possible to suppress the occurrence of watermarks on the substrate and the adhesion of foreign matter to the substrate.

The transparent plate may be disposed at a distance of 10 mm or less from the cup.

This will more reliably prevent mist of cleaning solution from bouncing off the cup and reaching the substrate.

The transparent plate may be made of any of the following materials: PEEK, PPS, PP, PE, PVC, PCTFE, PVDF, and PTFE.

This can effectively prevent corrosion caused by cleaning fluid.

The transparent plate can have a width of up to 100 mm in the vertical direction relative to the position of the substrate supported on the rotating table.

This type of device can also handle situations where the cleaning liquid randomly splashes in both the vertical and horizontal directions.

In addition, two exhaust ducts are provided,
The two exhaust ducts are located on opposite sides of the rotary table,
The exhaust dispersion plate is divided into a plurality of regions in a circumferential direction in a plan view,
The plurality of regions may be configured such that the ratio of an area occupied by the plurality of exhaust ports in a region increases as the region is farther away from the position of the exhaust duct.

This will ensure that the downflow airflow around the substrate is more uniform.

The substrate may be a rectangular substrate or a circular substrate.

The single-wafer cleaning apparatus of the present invention can be suitably used for such substrates.

The rectangular substrate is a photomask or a flat panel,
The circular substrate may be any one of a glass disk, a Si wafer, a Ge wafer, a GaAs wafer, and a SiC wafer.

The single-wafer cleaning apparatus of the present invention is particularly suitable for use with these substrates.

As described above, the single-wafer cleaning apparatus of the present invention can prevent mist caused by splashing of cleaning liquid from reaching the substrate, and can prevent the occurrence of watermarks on the substrate and the adhesion of foreign matter and metal components.

1A and 1B are a top view and a vertical sectional view showing an example of a single wafer cleaning apparatus according to the present invention; 10 is an explanatory diagram showing the effect of preventing the cleaning liquid from splashing onto the substrate by a transparent plate. FIG. 11 is a graph showing an example of the aperture ratio of each region in the exhaust dispersion plate and the wind speed of the downflow air current. FIG. 4 is a distribution diagram showing the average mist velocity on the substrate in Example 1 and Comparative Example 1. 1 is a graph showing the results of cross-sectional profiling in the flow direction of the substrate in Example 1 and Comparative Example 1. 1A and 1B are a top view and a vertical cross-sectional view showing the measurement positions of the mist amounts in Example 2 and Comparative Example 2. 13A and 13B are a top view and a vertical cross-sectional view showing the measurement positions of the mist amount in Example 3. 1A and 1B are a top view and a vertical sectional view showing an example of a conventional single wafer cleaning apparatus.

Hereinafter, the present invention will be described with reference to the drawings. However, the present invention is not limited to the embodiments.
(First embodiment)
1 shows a top view and a vertical cross-sectional view of an example of the single wafer cleaning apparatus of the present invention. The top view is shown on the upper side, and the vertical cross-sectional view is shown on the lower side. The single wafer cleaning apparatus 1 of the present invention has a table base 3, substrate holding pins 4, and a rotary table 5 on a bottom plate 2 of a processing chamber. Furthermore, a rotary motor 6, a back surface cleaning nozzle 7, and a front surface cleaning nozzle 8 are installed, and the front surface cleaning nozzle 8 is movable by a rotating arm 9 and an arm shaft 10. Note that, here, an example having two cleaning nozzles, one for the front surface and one for the back surface, is described, but the present invention is not limited to this, and for example, an example having one cleaning nozzle for either the front surface or the back surface may be used.

A cylindrical cup 11 is provided around the substrate W so as to surround the turntable 5, and an exhaust duct 12 is provided on the bottom plate 2 inside the cup 11 to form a downflow air current around the substrate W. Note that, although a description will be given here of two exhaust ducts 12 arranged on opposite sides of the turntable 5, the number and positions of the exhaust ducts 12 are not particularly limited.
The above configuration may be the same as that of the conventional single wafer cleaning apparatus 101, for example.
The first embodiment of the single wafer cleaning apparatus 1 of the present invention further includes both a permeable plate 13 and an exhaust gas dispersion plate 14. These two components will be described in detail below.

First, the permeable plate 13 will be described. FIG. 2 is an explanatory diagram showing the effect of the permeable plate in preventing the cleaning liquid from bouncing back onto the substrate W. The permeable plate 13 is disposed inside the cup 11, and is composed of a through hole 13a from the substrate side to the cup side, and a cleaning liquid shielding portion 13b. That is, the through hole 13a is formed in a plate-shaped main body, and the portion other than the through hole 13a is the cleaning liquid shielding portion 13b. When performing cleaning processing using the single-wafer cleaning apparatus 1, droplets of the cleaning liquid scattered from the substrate W by the rotation of the turntable 5 reach the cup 11 through the through hole 13a. The droplets that reach the cup 11 bounce back toward the substrate side as fine mist due to interference with the cup 11, but due to the presence of the permeable plate 13, they are blocked by the cleaning liquid shielding portion 13b, and the mist can be prevented from reaching the substrate W. As a result, the amount of watermarks and the like generated on the substrate can be suppressed.
The diameter size and distribution density of the through holes 13a are not particularly limited, but for example, through holes with a diameter of 5 mm can be uniformly distributed over the entire transparent plate.

The position of the permeable plate 13 is not particularly limited, but it can be located, for example, at a distance of 10 mm or less from the cup 11. This can more reliably prevent the mist of cleaning liquid that bounces off the cup 11 from reaching the substrate W.

The material of the permeable plate 13 is not particularly limited, but it can be made of any of the following materials, for example: PEEK, PPS, PP, PE, PVC, PCTFE, PVDF, and PTFE. Such materials can effectively prevent corrosion caused by the cleaning liquid.

Furthermore, the vertical width of the transparent plate 13 is not particularly limited, but may be, for example, within 100 mm in the vertical direction relative to the position of the substrate W supported by the turntable 5 .
In single-wafer cleaning equipment, the cleaning liquid tends to scatter in a position almost horizontal to the substrate when rotating at high speeds of, for example, 600 rpm or more, but when processing a thick rectangular substrate, for example, the outer periphery protruding from the inner periphery affects the cleaning liquid, which tends to scatter randomly over a wide range in the vertical direction relative to the horizontal position of the substrate, so it is better to position the permeable plate at a wider angle in the vertical direction than in the horizontal position. A permeable plate with a width of 100 mm or less in the vertical direction can also handle cases where the cleaning liquid scatters randomly in the vertical direction like this.

Next, the exhaust dispersion plate 14 will be described. As shown in FIG. 1, the exhaust dispersion plate 14 is disposed above the bottom plate 2 and on the inside of the cup 11 as a raised bottom, so as to cover the table base 3 in a circular (ring-like) shape. It has a plurality of exhaust ports 16 through which the airflow flows from the substrate W side to the exhaust duct 12 side, and the downflow airflow around the substrate W is blocked by the airflow blocking portion 15 and flows through the exhaust ports 16 to the exhaust duct 12. In this way, the airflow passes through the plurality of exhaust ports 16, so that the downflow airflow around the substrate can be made uniform, and as a result, it is possible to prevent the mist of the cleaning liquid from reaching the substrate even in a position where the downflow was weak in the past (a position far from the exhaust duct 12).

The configuration of the exhaust dispersion plate 14 is not particularly limited, but in the case of the two exhaust ducts 12 as shown in FIG. 1 arranged on the opposite sides of the rotary table 5, for example, the exhaust dispersion plate 14 is divided into a plurality of regions 17 in the circumferential direction in a plan view, and the ratio (opening ratio) of the area occupied by the plurality of exhaust ports 16 in the region 17 can be made larger as the region is farther from the position of the exhaust duct 12. That is, if the exhaust dispersion plate 14 is divided into four types of regions 17a to 17d as shown in FIG. 1, the opening ratio of the region 17a directly above the exhaust duct 12 can be made the smallest, followed by 17b, 17c, and 17d in that order. In this case, the downflow airflow around the substrate can be more reliably made uniform, and the mist of the cleaning liquid that bounces off the cup 11 or the permeable plate 13 toward the substrate can be more efficiently prevented from reaching the substrate. The exhaust dispersion plate 14 can be not only divided into one plate, but also, for example, a plurality of plates (divided plates) with different opening ratios for each region can be arranged side by side. The partitions may be bonded together between adjacent ones.
The size of the exhaust port 16 is not particularly limited, but may be, for example, 6 mm or less in diameter.

Fig. 3 is a graph showing an example of the aperture ratio of each region in the exhaust dispersion plate and the wind speed of the downflow air current. As shown in the lower diagram in Fig. 3, regions 17a to 17d are divided into four types of areas, 1 to 4, in order from the region closest to exhaust duct 12. The graph on the left side of Fig. 3 shows the aperture ratio of each region, and the aperture ratio increases as the distance from the position of exhaust duct 12 increases. Note that the multiple exhaust ports are arranged in a lattice pattern, and the aperture ratio can be calculated by the following formula.
Opening ratio [%] = (D ² /P ² ) x 78.5
(D: exhaust port diameter [mm], P: center distance between adjacent exhaust ports [mm])
That is, it is the area of the exhaust port 16 per unit area of the exhaust dispersion plate 14. This formula is obtained by dividing the area of the exhaust port 16, π·(D/2) ² , by the area surrounded by four adjacent exhaust ports, P ² , and multiplying the result by 100.
The wind speed of the downflow air current was measured in the single wafer cleaning apparatus 1 of the present invention using such an exhaust dispersion plate 14. As a result, as shown in the graph on the right side of FIG. 3, it can be seen that the downflow air current in each area is uniform.

The substrate W may be, for example, a square substrate or a circular substrate. The square substrate may be a photomask or a flat panel. The circular substrate may be any of a glass disk, a Si wafer, a Ge wafer, a GaAs wafer, and a SiC wafer. Cleaning using the single-wafer cleaning apparatus of the present invention is particularly suitable for these substrates, but is not limited to these.

(Second embodiment)
1 has been described as an example having both the permeable plate 13 and the exhaust dispersion plate 14, but as another embodiment, it is also possible to have only the permeable plate 13 and not the exhaust dispersion plate 14. In this case as well, the effect of blocking the mist of the cleaning liquid rebounded from the cup 11 by the permeable plate 13 can be obtained, so that the mist of the cleaning liquid can be prevented from reaching the substrate W.

(Third embodiment)
As yet another embodiment, the apparatus may have only the exhaust dispersion plate 14 and not the permeable plate 13. In this case as well, the effect of uniformizing the downflow airflow around the substrate can be obtained, and therefore the mist of the cleaning liquid can be prevented from reaching the substrate W.

As in the second and third embodiments, even if only one of the permeable plate 13 and the exhaust dispersion plate 14 is included, it is possible to prevent the mist of the cleaning liquid from reaching the substrate W more reliably than in the past, but the first embodiment, which has both of these, can prevent this more reliably.

The present invention will be described in more detail below with reference to examples and comparative examples of the present invention, but the present invention is not limited to these.
Example 1
Measurements of airflow were carried out in the following steps 1 to 5 using the third embodiment described above, i.e., the single wafer cleaning apparatus 1 of the present invention shown in Fig. 1, which has only the exhaust dispersion plate 14 and does not have the permeable plate 13. The exhaust dispersion plate 14 used was divided into four types of regions with opening ratios as shown in Fig. 3.
1. An airflow visualization mist was flowed onto the substrate, and the substrate was rotated at 1,500 rpm.
2. A high-speed camera was installed outside the treatment room and filmed at 250 fps.
3. The captured images were processed to calculate the mist flow velocity.
4. 1,000 frames of data were averaged to perform a distribution study on the mist flow direction on the substrate.
5. In addition, a cross-sectional profile was taken in the flow direction of the substrate to measure the fluctuation state of the air flow.

(Comparative Example 1)
Measurements were carried out in the same manner as in Example 1, except that a conventional single-wafer cleaning apparatus 101 shown in FIG. 8 was used.

Figure 4 is a distribution diagram showing the average mist velocity on the substrate. The top side shows Example 1, and the bottom side shows Comparative Example 1. The average mist velocity distribution was obtained by using fluid analysis software: Flownizer2D2C (DITECT) to determine the displacement vector at each point in a specified range of the captured image using the correlation method, and then calculating the average value of the vector group within the range at a certain timing (frame). In the external average mist velocity distribution, areas where no flow occurs (arrows in the lower diagram) can be confirmed in Comparative Example 1, indicating that the airflow is unstable. On the other hand, a uniform flow (arrows in the upper diagram) was observed in Example 1.

Figure 5 is a graph showing the results of a cross-sectional profile taken in the flow direction of the substrate. The horizontal axis shows the frame number, and the vertical axis shows the velocity in the tangent vector direction obtained from the UV coordinate system. This velocity was obtained by calculating the average velocity by elapsed time (frame) at a certain position (the same position in Example 1 and Comparative Example 1, the position indicated by the arrow in Figure 4) from the average mist velocity distribution calculated as described above. Table 1 also shows the results of calculating the coefficient of variation (σ/AVE) from Figure 5.

As shown in Table 1, when the coefficient of variation (σ/AVE) was calculated and compared, it was confirmed that the coefficient of variation was small in Example 1, meaning that there was less airflow variation above the substrate.

Example 2
In the second embodiment described above, that is, in the single-wafer cleaning apparatus 1 of the present invention shown in FIG. 1, only the permeable plate 13 was used, and the exhaust dispersion plate 14 was not included. Pure water was supplied to the center of the substrate, and the amount of mist was measured while rotating the substrate. The permeable plate 13 had through holes with a diameter of 5 mm uniformly distributed over the entire permeable plate, and was disposed at a position 5 mm away from the cup 11. The material used was PTFE, and the width in the vertical direction was 100 mm. The rotation speed was 1,000 rpm and 1,500 rpm, which are generally used in drying processing. The measurement position of the amount of mist was 50 mm above the substrate, where the airflow on the substrate was weak in the conventional single-wafer cleaning apparatus, and the measurement time was 3 minutes. FIG. 6 shows the mist amount measurement position 18. The upper side shows a vertical cross-sectional view, and the lower side shows a top view.

(Comparative Example 2)
The mist amount was measured in the same manner as in Example 2, except that a conventional single-wafer cleaning apparatus 101 shown in FIG. 8 was used.
Table 2 shows the measurement results of the amount of mist in Example 2 and Comparative Example 2, and the reduction rate of the amount of mist in Example 2 compared to Comparative Example 2, which is a conventional technique.

As shown in Table 2, in Example 2, the mist suppression effect of the permeable plate near the cup was confirmed.

Example 3
In the first embodiment described above, that is, the single wafer cleaning apparatus 1 of the present invention shown in FIG. 1, which has both a permeable plate 13 and an exhaust dispersion plate 14, pure water was supplied to the center of the substrate and the amount of mist was measured while rotating the substrate. The same exhaust dispersion plate 14 as in Example 1 was used, and the rotation speed was 1,500 rpm. The mist amount was measured on the substrate in each of the four regions 1 to 4 of the exhaust dispersion plate 14. The measurement time was 3 minutes. FIG. 7 shows the mist amount measurement position 18. The upper side shows a vertical cross-sectional view, and the lower side shows a top view.
Table 3 shows the measurement results of the amount of mist in Example 3 and Comparative Example 2, and the reduction rate of the amount of mist in Example 3 compared to Comparative Example 2, which is a conventional technique.

As shown in Table 3, in Example 3, a higher mist suppression effect was confirmed due to both the mist suppression effect of the permeable plate bouncing off the cup toward the substrate, and the mist suppression effect in the processing chamber where the airflow around the substrate is made uniform by the exhaust dispersion plate. It was also found that the amount of mist in each area was roughly the same due to the uniformity of the downflow airflow around the substrate.

From the above results, the single-wafer cleaning equipment of the present invention can prevent mist caused by splashing of cleaning liquid from reaching the substrate, thereby preventing the adhesion of foreign matter caused by the mist and the occurrence of watermarks.

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... single wafer cleaning apparatus of the present invention; 2, 102... bottom plate;
3, 103...table base; 4, 104...substrate holding pin;
5, 105...rotary table; 6, 106...rotary motor;
7, 107... rear surface cleaning nozzle; 8, 108... front surface cleaning nozzle;
9, 109... Swivel arm; 10, 110... Arm shaft; 11, 111... Cup;
12, 112...exhaust duct; 13...permeable plate; 13a...through hole;
13b: cleaning liquid shielding portion; 14: exhaust dispersion plate; 15: airflow shielding portion;
16... exhaust port; 17, 17a, 17b, 17c, 17d... areas;
18: mist amount measuring position; 101: conventional single wafer cleaning apparatus; W: substrate.

Claims (7)

The bottom plate and
a rotary table that is disposed on the bottom plate and that supports and rotates a substrate to be cleaned;
a cleaning nozzle for supplying a cleaning liquid to the substrate;
a cylindrical cup disposed on the bottom plate so as to surround the turntable and configured to prevent the cleaning liquid supplied to the substrate from scattering;
an exhaust duct disposed on the bottom plate at a position inside the cup and forming a downflow air current around the substrate,
a cylindrical permeable plate that is disposed inside the cup, has a through hole from the substrate side to the cup side, and allows the cleaning liquid splashed from the substrate to pass through the through hole to the cup side, and prevents the cleaning liquid that has passed through the cup side and rebounded from the cup from reaching the substrate;
an exhaust dispersion plate, which is a raised bottom disposed above the bottom plate and inside the cup, and has a plurality of exhaust ports from the substrate side to the exhaust duct side, and through which the downflow airflow around the substrate flows into the exhaust duct through the exhaust ports ;
A single wafer cleaning apparatus, characterized in that the through holes are uniformly distributed over the entire surface of the permeable plate . The single wafer cleaning apparatus according to claim 1, characterized in that the permeable plate is disposed at a distance of 10 mm or less from the cup. The single wafer cleaning apparatus according to claim 1 or 2, characterized in that the transparent plate is made of any one of the following materials: PEEK, PPS, PP, PE, PVC, PCTFE, PVDF, and PTFE. A single-wafer cleaning apparatus according to any one of claims 1 to 3, characterized in that the transparent plate has a width of 100 mm or less in the vertical direction relative to the position of the substrate supported on the rotating table. The exhaust duct is provided in two pieces.
The two exhaust ducts are located on opposite sides of the rotary table,
The exhaust dispersion plate is divided into a plurality of regions in a circumferential direction in a plan view,
5. The single wafer cleaning apparatus according to claim 1, wherein the ratio of an area of the plurality of regions occupied by the plurality of exhaust ports in the plurality of regions increases as the area of the plurality of regions is farther from the position of the exhaust duct. A single-wafer cleaning apparatus according to any one of claims 1 to 5, characterized in that the substrate is a square substrate or a circular substrate. the rectangular substrate is a photomask or a flat panel,
7. The single-wafer cleaning apparatus according to claim 6 , wherein the circular substrate is any one of a glass disk, a Si wafer, a Ge wafer, a GaAs wafer, and a SiC wafer.

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