WAFER CLEANING DEVICE

Abstract

Wafer cleaning device (1) for cleaning a peripheral edge (101) of a wafer (100), the wafer cleaning device (1) comprising: a holding table (10) which holds the wafer (100) by a holding surface (11) such that the peripheral edge (101) of the wafer (100) protrudes; a motor (15) which rotates the holding table (10) with a center of the holding surface (11) as an axis, a rotation control section (17) that controls a rotation speed of the motor (15); and a cleaning unit (20) which ejects high-pressure water toward the peripheral edge (101) of the wafer (100) from an outer side with respect to the peripheral edge (101) of the wafer (100) held by the holding surface (11) to clean the peripheral edge (101) of the wafer (100), wherein the cleaning unit (20) comprises: a first nozzle (21) which ejects the high-pressure water to the peripheral edge (101) of the wafer (100) from the outer side with respect to the peripheral edge (101) of the wafer (100) in a 0-degree direction parallel to the holding surface (11), a second nozzle (24) which ejects the high-pressure water to the peripheral edge (101) of the wafer (100) from an outer upper side with respect to the peripheral edge (101) of the wafer (100) in a direction of 45 degrees downward relative to the holding surface (11), and a third nozzle (27) which ejects the high-pressure water to the peripheral edge (101) of the wafer (100) from an outer lower side with respect to the peripheral edge (101) of the wafer (100) in a direction of 45 degrees upward relative to the holding surface (11), and wherein the first nozzle (21), the second nozzle (24) and the third nozzle (27) are arranged so as to be spaced apart from each other in a circumferential direction of the wafer (100).

Description

BACKGROUND OF THE INVENTIONTechnical field

[0001] The present invention relates to a wafer cleaning apparatus. Description of the state of the art

[0002] During wafer production, a wafer with a waviness and / or warpage is obtained by cutting a semiconductor ingot. To remove the waviness and / or warpage from this wafer, a protective member comprising a plastic and a film is formed on a surface on one side of the wafer, as disclosed in JP 2017-168565 A.

[0003] Then, the surface on one side of the wafer is held by a chuck table through the protective member, and a surface on the other side of the wafer is ground by a grindstone to thereby remove the waviness and / or warpage.

[0004] After grinding the surface of the other side of the wafer, the protective member is peeled off, and the surface of one side of the wafer is ground, as disclosed in JP 2018-98241 A. As a result, a wafer with a predetermined thickness is produced.

[0005] When peeling the protective element from the wafer, the plastic may remain at the peripheral edge of the wafer. In view of this, the peripheral edge of the wafer is cleaned with a cleaning tool, thereby removing the adhering plastic, as disclosed in JP 2019-47054 A.

[0006] Further prior art helpful for understanding the present invention can be found in the following documents: US 2003 / 0 098 040 A1 relates to a cleaning device including upper and lower nozzle arrangements for supplying a cleaning liquid to end and bottom portions of a semiconductor substrate. US 2003 / 0 168 089 A1 relates to a device that continuously supplies an acidic solution to a central portion of a substrate while the substrate rotates. SUMMARY OF THE INVENTION

[0007] However, the conventional cleaning method has a problem in that due to the consumption of a sponge as the cleaning tool, the cost of replacing the cleaning tool is incurred.

[0008] Accordingly, it is an object of the present invention to provide a wafer cleaning apparatus capable of removing a plastic adhering to a peripheral edge of a wafer without using a cleaning tool.

[0009] According to one aspect of the present invention, a wafer cleaning apparatus for cleaning a peripheral edge of a wafer is provided, the wafer cleaning apparatus comprising: a holding table that holds the wafer by a holding surface such that the peripheral edge of the wafer protrudes; a motor that rotates the holding table with the center of the holding surface as an axis; a rotation control section that controls a rotation speed of the motor; and a cleaning unit that ejects high-pressure water toward the peripheral edge of the wafer from an outer side with respect to the peripheral edge of the wafer held by the holding surface to clean the peripheral edge of the wafer, the cleaning unit comprising: a first nozzle that ejects the high-pressure water toward the peripheral edge of the wafer from the outer side with respect to the peripheral edge of the wafer in a 0-degree direction parallel to the holding surface; a second nozzle,which ejects the high-pressure water to the peripheral edge of the wafer from an outer upper side with respect to the peripheral edge of the wafer in a direction of 45 degrees downward relative to the holding surface, and a third nozzle which ejects the high-pressure water to the peripheral edge of the wafer from an outer lower side with respect to the peripheral edge of the wafer in a direction of 45 degrees upward relative to the holding surface, and wherein the first nozzle, the second nozzle, and the third nozzle are arranged so as to be spaced apart from each other in a circumferential direction of the wafer.

[0010] Preferably, the cleaning unit is configured to eject the high-pressure water using air pressure by mixing water and air.

[0011] Preferably, the rotation control section is configured to rotate the holding table at a rotation speed equal to or less than 10 rpm to clean the periphery of the wafer, and thereafter rotate the holding table at a rotation speed equal to or more than 1,000 rpm to dry the wafer.

[0012] According to the present wafer cleaning apparatus, high-pressure water is jetted from three different directions toward the peripheral edge of the wafer, allowing the peripheral edge to be completely cleaned and the plastic or the like adhering to the peripheral edge to be removed. Therefore, the present wafer cleaning apparatus eliminates the need for a cleaning tool such as a sponge as a consumable for cleaning the peripheral edge. Consequently, a cleaning tool replacement process is unnecessary, thus eliminating the cost of replacing the cleaning tool.

[0013] The above and other objects, features and advantages of the present invention and the modes for carrying them out will become more apparent and the invention itself will be best understood by studying the following description and the appended claims with reference to the accompanying drawings which show a preferred embodiment of the invention. SHORT DESCRIPTION OF THE FIGURES Fig. 1 is a side view illustrating the configuration of a wafer cleaning apparatus; Fig. 2 is a plan view showing a wafer, a holding table, and nozzles of a cleaning unit; and Fig. 3 is a side view illustrating another embodiment of the wafer cleaning apparatus. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0014] As in Fig. 1, a wafer cleaning apparatus 1 according to the present embodiment is for cleaning a peripheral edge 101 of a wafer 100. The peripheral edge 101 is chamfered in an arc shape from a surface on one side of the wafer 100 to a surface on the other side of the wafer 100 and is rounded.

[0015] Furthermore, the wafer 100 has already been ground, and a protective member formed on a surface thereof has been peeled off. Therefore, a contaminant such as a plastic, which is the material of the protective member, adheres to the peripheral edge 101 of the wafer 100. The wafer cleaning device 1 cleans the peripheral edge 101 of the wafer 100 to remove the contaminant such as this plastic.

[0016] The wafer cleaning apparatus 1 includes a holding table 10 for holding the wafer 100. The holding table 10 has a holding surface 11 that is smaller than the wafer 100. The holding surface 11 comprises, for example, a porous material and can suck the wafer 100 by connecting it to a suction source (not shown). Therefore, the holding table 10 holds the wafer 100 through the holding surface 11 in such a way that the peripheral edge 101 of the wafer 100 protrudes.

[0017] The wafer cleaning apparatus 1 further includes a spindle 13 provided on the lower side of the holding table 10, a motor 15 for rotating the spindle 13, and a rotation control section 17 that controls a rotation speed of the motor 15.

[0018] The spindle 13 is configured to rotate with the center of the holding surface 11 as an axis. By rotating the spindle 13, the motor 15 can rotate the holding table 10 with the center of the holding surface 11 as an axis, as indicated by an arrow 200.

[0019] The wafer cleaning apparatus 1 further includes a cleaning unit 20 on the outer side of the peripheral edge 101 of the wafer 100 held by the holding surface 11 of the holding table 10. The cleaning unit 20 jets high-pressure water from the outer side relative to the peripheral edge 101 of the wafer 100 held by the holding surface 11 toward the peripheral edge 101 of the wafer 100, for example, toward the center in the thickness direction of the peripheral edge 101, to thereby clean the peripheral edge 101 of the wafer 100.

[0020] As in Fig. 1, the cleaning unit 20 has three nozzles, namely a first nozzle 21, a second nozzle 24 and a third nozzle 27.

[0021] As in Fig. 1 by an arrow 201, the first nozzle 21 ejects the high-pressure water to the peripheral edge 101 of the wafer 100 from the outer side with respect to the peripheral edge 101 of the wafer 100 in a 0-degree direction parallel to the holding surface 11 of the holding table 10.

[0022] As in Fig. 1 by an arrow 202, the second nozzle 24 ejects the high-pressure water toward the peripheral edge 101 of the wafer 100 from the outer upper side with respect to the peripheral edge 101 of the wafer 100, in a direction of 45 degrees downward relative to the holding surface 11 of the holding table 10.

[0023] As in Fig. 1 by an arrow 203, the third nozzle 27 ejects the high-pressure water toward the peripheral edge 101 of the wafer 100 from the outer lower side with respect to the peripheral edge 101 of the wafer 100, in a direction of 45 degrees upward relative to the holding surface 11 of the holding table 10.

[0024] In addition, as in Fig. As shown in Figure 2, the first nozzle 21, the second nozzle 24, and the third nozzle 27 are spaced apart from each other in the circumferential direction of the wafer 100 at a distance of, for example, 10 degrees. The direction of the high-pressure water jetted from the first nozzle 21, the second nozzle 24, and the third nozzle 27 is on a horizontal plane (a plane parallel to the support surface 11), for example, toward a center point 12, which is the center in the radial direction of the support surface 11 (the center of the wafer 100).

[0025] In addition, the cleaning unit 20 is designed to eject the high-pressure water using the pressure of air by mixing water and air. In other words, the first nozzle 21, the second nozzle 24, and the third nozzle 27 are arranged as shown in Fig. 1, connected to an air source 22 and a water source 23, to an air source 25 and a water source 26, or to an air source 28 and a water source 29.

[0026] Then, the first nozzle 21, the second nozzle 24, and the third nozzle 27 are configured to mix the water from the respective water sources 23, 26, and 29 and the air from the respective air sources 22, 25, and 28 to generate the high-pressure water using the pressure of the air, in other words, the high-pressure water having a binary cleaning fluid mixed from the water and the air, and to jet the high-pressure water.

[0027] In this way, the first nozzle 21, the second nozzle 24, and the third nozzle 27 act as binary liquid cleaning nozzles. Note that the first nozzle 21, the second nozzle 24, and the third nozzle 27 are designed to be able to only discharge air from the respective air sources 22, 25, and 28, and only discharge water from the respective water sources 23, 26, and 29. The cleaning unit 20, comprising the first nozzle 21, the second nozzle 24, and the third nozzle 27, is connected by a Fig. 1 shown cleaning control section 30.

[0028] An operation of the wafer cleaning apparatus 1 is described below. (cleaning process)

[0029] First, a cleaning process is performed. During this process, the wafer 100 is initially held by the holding surface 11 of the holding table 10.

[0030] Thereafter, the cleaning control section 30 supplies, for example, 40 ml / min of water from the water sources 23, 26, and 29 to the first nozzle 21, the second nozzle 24, and the third nozzle 27, and supplies, for example, 70 l / min of air from the air sources 22, 25, and 28 to the nozzles 21, 24, and 27. The first nozzle 21, the second nozzle 24, and the third nozzle 27 mix the water and the air supplied thereto to generate high-pressure water containing the binary fluid cleaning water, and begin to eject the high-pressure water toward the peripheral edge 101 of the wafer 100 in the respective specified directions described above.

[0031] Next, the rotation control section 17 controls the motor 15 to rotate the holding table 10 with the wafer 100 held by the holding surface 11 once at a speed of 10 rpm or less (e.g., 1 rpm). This completes cleaning of the wafer 100, and the rotation control section 17 stops the rotation of the holding table 10 by the motor 15. At the same time, the cleaning control section 30 stops the supply of water and air to the first nozzle 21, the second nozzle 24, and the third nozzle 27. Through this cleaning operation, contaminants such as plastic adhering to the peripheral edge 101 of the wafer 100 are removed.

[0032] Note that in the present embodiment, rotating the wafer 100 once means that the wafer 100 is rotated so that the three portions of the water jetted from the first nozzle 21, the second nozzle 24, and the third nozzle 27 are blown at high pressure onto the entire part of the peripheral edge 101 of the wafer 100.

[0033] As in Fig. As shown in Figure 2, the first nozzle 21, the second nozzle 24, and the third nozzle 27 are arranged spaced apart from each other in the circumferential direction of the wafer 100. Therefore, the angle of rotation of a single rotation by the amount corresponding to the angular range of the nozzle arrangement is greater than 360 degrees.

[0034] For example, in a case where the first nozzle 21, the second nozzle 24, and the third nozzle 27 are arranged at intervals of 10 degrees in the circumferential direction of the wafer 100, rotating the wafer 100 once means rotating the wafer 100 by about 380 degrees. [Drying process]

[0035] Next, a drying process is performed. In the drying process, first, the rotation control section 17 controls the motor 15 to rotate the holding table 10 with the wafer 100 held by the holding surface 11 at a rotation speed equal to or greater than 1,000 rpm (e.g., 2,000 rpm) for, for example, 20 seconds. In this case, in the first 15 seconds, air ejection and the like from the cleaning unit 20 are not performed, and the water adhering to the wafer 100 is splashed by the rotation of the holding table 10 holding the wafer 100. Note that the rotation of the holding table 10 may not be stopped during the cleaning process and may be switched to the rotation speed of the drying process immediately after the cleaning process.

[0036] When 15 seconds have passed since the rotation of the holding table 10, the cleaning control section 30 supplies air from the air sources 22, 25, and 28 to the first nozzle 21, the second nozzle 24, and the third nozzle 27 for five seconds and starts ejecting air from these nozzles toward the wafer 100. During the five seconds, air is supplied to the rotating wafer 100 from three directions, thereby assisting in drying the wafer 100.

[0037] After five seconds from the start of the air supply, i.e., 20 seconds from the start of the drying process, the rotation control section 17 stops the rotation of the holding table 10 by the motor 15, determining that the drying of the wafer 100 is complete. At the same time, the cleaning control section 30 stops the air supply to the first nozzle 21, the second nozzle 24, and the third nozzle 27.

[0038] As described above, in the present embodiment, high-pressure water is jetted from three different directions toward the peripheral edge 101 of the wafer 100, thereby cleaning the peripheral edge 101, which is rounded, all around, and removing contaminants such as plastic adhering to the peripheral edge 101. Therefore, in the present embodiment, a cleaning tool such as a sponge is not required as a consumable for cleaning the peripheral edge 101. Consequently, a cleaning tool replacement operation is not required, so the cost of replacing the cleaning tool can be avoided.

[0039] It should be noted that in the present embodiment, at the time of the drying process, air is jetted from the first nozzle 21, the second nozzle 24 and the third nozzle 27 to the wafer 100. With respect to this, as shown in Fig.3, the wafer cleaning apparatus 1 may further include an air nozzle 40. The air nozzle 40 is arranged on the upper side of the center of the wafer 100 held by the holding surface 11 of the holding table 10 and is configured to eject air toward the wafer 100, as shown by an arrow 205.

[0040] In this case, during the drying process, the cleaning control section 30 jets air from the air nozzle 40 toward the wafer 100, instead of or in addition to jets of air onto the wafer 100 from the first nozzle 21, the second nozzle 24, and the third nozzle 27. Since the air nozzle 40 jets air toward the rotation center of the wafer 100, the drying time can be shortened. Additionally, air could be jetted onto the periphery of the holding table 10 to dry the lower surface of the wafer 100.

[0041] In the present embodiment, at the time of the cleaning operation, the rotation control section 17 controls the holding table 10 holding the wafer 100 once. In this regard, the rotation control section 17 may rotate the holding table 10 twice or more, and it may rotate the holding table 10 360 degrees.

[0042] Furthermore, in the present embodiment, drying is performed only by rotating the holding table 10 for 15 seconds, and then drying is performed with additional air discharge from the cleaning unit 20 for five seconds. In this regard, the drying time only by rotating the holding table 10 and the drying time with additional air discharge could be optionally set.

[0043] Furthermore, in the present embodiment, the first nozzle 21, the second nozzle 24, and the third nozzle 27 are provided with the air sources 22, 25, and 28, and the water sources 23, 26, and 29, respectively. Instead, the first nozzle 21, the second nozzle 24, and the third nozzle 27 could be configured to communicate with a common air source and a common water source.

[0044] The present invention is not limited to the details of the preferred embodiment described above. The scope of the invention is defined by the appended claims, and all changes and modifications that fall within the scope of the claims are therefore intended to be encompassed by the invention.

Claims

[1] Wafer cleaning device (1) for cleaning a peripheral edge (101) of a wafer (100), wherein the wafer cleaning device (1) comprises: a holding table (10) which holds the wafer (100) by means of a holding surface (11) such that the circumferential edge (101) of the wafer (100) protrudes; a motor (15) that rotates the holding table (10) with a center of the holding surface (11) as an axis, a rotation control section (17) that controls the rotational speed of the motor (15); and a cleaning unit (20) which ejects high-pressure water towards the circumferential edge (101) of the wafer (100) from an outer side with respect to the circumferential edge (101) of the wafer (100) held by the holding surface (11) in order to clean the circumferential edge (101) of the wafer (100), wherein the cleaning unit (20) has: a first nozzle (21) that ejects the high-pressure water to the circumferential edge (101) of the wafer (100) from the outer side with respect to the circumferential edge (101) of the wafer (100) in a 0-degree direction parallel to the holding surface (11), a second nozzle (24) that ejects the high-pressure water to the circumferential edge (101) of the wafer (100) from an outer upper side in relation to the circumferential edge (101) of the wafer (100) in a direction of 45 degrees downwards relative to the holding surface (11), and a third nozzle (27) that ejects the high-pressure water to the circumferential edge (101) of the wafer (100) from an outer lower side in relation to the circumferential edge (101) of the wafer (100) in a direction of 45 degrees upwards relative to the holding surface (11), and wherein the first nozzle (21), the second nozzle (24) and the third nozzle (27) are arranged such that they are spaced apart from each other in a circumferential direction of the wafer (100). [2] Wafer cleaning device (1) according to claim 1, wherein the cleaning unit (20) is configured to expel the high-pressure water using pressure from air by mixing water and air. [3] Wafer cleaning device (1) according to claim 1 or 2, wherein the rotation control section (17) is configured to rotate the holding table (10) at a rotational speed of 10 rpm or less to clean one circumference of the wafer (100), and then to rotate the holding table (10) at a rotational speed of 1,000 rpm or more to dry the wafer (100).

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