Abstract
A rotor disk for guiding workpieces in a double-sided processing machine including a fluid feeding apparatus to feed a processing fluid into a working gap between a first working disk and a second working disk is provided. The rotor disk comprises a surface defining at least one workpiece opening configured to receive at least one workpiece to be processed on both sides in the double-sided processing machine in a material-removing manner using the processing fluid. A contact angle of a drop of the processing fluid with the surface is at least 60°.
Claims
1. A rotor disk for guiding workpieces in a double-sided processing machine including a fluid feeding apparatus to feed a processing fluid into a working gap between a first working disk and a second working disk, the rotor disk comprising: a surface defining at least one workpiece opening configured to receive at least one workpiece to be processed on both sides in the double-sided processing machine in a material-removing manner using the processing fluid, wherein a contact angle of a drop of the processing fluid with the surface is at least 60°.
2. The rotor disk according to claim 1, wherein the contact angle of the drop of the processing fluid is not more than 90°.
3. The rotor disk according to claim 1, wherein the contact angle of the drop of the processing fluid is not more than 75°.
4. The rotor disk according to claim 1, wherein the surface of the rotor disk is roughened.
5. The rotor disk according to claim 1, wherein the surface of the rotor disk is covered with a coating.
6. The rotor disk according to claim 5, wherein the coating is a DLC coating.
7. A double-sided processing machine comprising: a first working disk comprising a first working surface; a second working disk comprising a second working surface, wherein the first and second working surfaces delimit a working gap between them, and wherein at least one of the first working disk and the second working disk is configured to be rotatingly driven; a fluid feed configured to feed a processing fluid into the working gap; and at least one rotor disk comprising a surface that defines at least one workpiece opening configured to receive at least one workpiece to be processed on both sides in a material-removing manner using the processing fluid, wherein a contact angle of a drop of the processing fluid with the surface of the rotor disk is at least 60°.
8. The double-sided processing machine according to claim 7, wherein the at least one workpiece is received in the at least one workpiece opening of the at least one rotor disk and is guided for processing in the working gap of the double-sided processing machine.
9. The double-sided processing machine according to claim 8, wherein at least one of the first working disk and the second working disk is rotatingly driven, and wherein the processing fluid is fed into the working gap during processing.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
[0017] Exemplary embodiments of the invention will be explained in greater detail below with reference to figures, wherein:
[0018] FIG. 1 illustrates a cross-sectional view of a schematic depiction of an embodiment of a double-sided processing machine;
[0019] FIG. 2 illustrates a top plan view of a schematic depiction of an embodiment of a rotor disk of an embodiment of the double-sided processing machine;
[0020] FIG. 3 illustrates a top plan view of a schematic depiction of another embodiment of a rotor disk of an embodiment of the double-sided processing machine; and
[0021] FIG. 4 illustrates a diagram showing average thickness profiles of different workpieces subjected to double-sided processing in a material-removing manner.
[0022] Unless otherwise indicated, the same reference numerals denote the same objects in the figures.
DETAILED DESCRIPTION OF THE INVENTION
[0023] In FIG. 1, a double-sided processing machine according to the invention, in particular a double-sided polishing machine, is depicted schematically. The double-sided processing machine includes an upper carrier disk 10 and a lower carrier disk 12 arranged opposite the upper carrier disk 10. The upper carrier disk 10 carries an upper working disk 14 and the lower carrier disk 12 carries a lower working disk 16. The working disks 14, 16 can, by way of example, be provided with a polishing covering, in particular a polishing pad. The carrier disks 10, 12 and, with them, the working disks 14, 16 can be rotatingly driven around their axis 26 which runs vertically in FIG. 1 by way of drive shafts 18, 20, in particular in opposite directions during operation of the double-sided processing machine.
[0024] The working disks 14, 16 delimit between them a working gap 22. Multiple rotor disks 24 are arranged in the working gap. In FIG. 1, two rotor disks 24 are depicted. Of course, more or less than two rotor disks can also be provided. Workpieces 28, for example semiconductor wafers, for example made of silicon, which are to be processed in a material-removing manner on both sides, are held in a floating manner in the workpiece openings of the rotor disks 24 in the working gap 22. The rotor disks 24 usually have, at their outer edge, outer teeth which are not depicted in greater detail in FIG. 1 which are in mesh with inner teeth which are arranged on the inner edge of the working gap 22, which are not depicted in greater detail in FIG. 1, as well as outer teeth which are arranged on the outer edge of the working gap 22, which are likewise not depicted in greater detail in FIG. 1. As a result, the rotor disks 24 are rotated along a circular path through the working gap 22 and additionally about their axes during operation, so that the workpieces 28 move along cycloid tracks through the working gap 22. By means of a fluid feed which is depicted schematically in FIG. 1 with the reference numeral 30, a processing fluid, in particular a polishing fluid (slurry) is fed into the working gap 22 during operation. The surface of the rotor disks 24 has a contact angle of a water drop of at least 60°. For example, the surface of the rotor disk 24 can be mechanically roughened in order to achieve said contact angle. The surface of the rotor disk 24, which can consist by way of example of stainless steel, can, alternatively or additionally to roughening, also be provided with a coating, for example a DLC coating, in order to achieve the desired contact angle.
[0025] In FIG. 2, a further rotor disk 124 according to the invention is shown, which can be utilized in the double-sided processing machine shown in FIG. 1. The rotor disk 124 has, in the example shown, three circular workpiece openings 132, in which workpieces for processing can be received in a floating manner. In addition, the outer teeth 134 can be seen in the case of the rotor disk 124 in FIG. 2. The rotor disk 124 shown in FIG. 2 also has a contact angle of a water drop of at least 60°. For example, the surface of the rotor disk 124 can be mechanically roughened in order to achieve said contact angle. The surface of the rotor disk 124, which can consist by way of example of stainless steel, can also, alternatively or additionally to roughening, be provided with a coating, for example a DLC coating, in order to achieve the desired contact angle.
[0026] FIG. 3 shows a further exemplary embodiment of a rotor disk 224 which can likewise be utilized in the double-sided processing machine shown in FIG. 1. As shown, the rotor disk 224 defines three circular workpiece openings 232 for receiving workpieces to be processed in a floating manner as well as outer teeth 234. Unlike the rotor disk 124 shown in FIG. 2, the rotor disk 224 shown in FIG. 3 has, in addition to the three workpiece openings 232, multiple auxiliary openings 236. The fed processing fluid can collect in the auxiliary openings 236 during the processing of the workpieces in the working gap 22 of the double-sided processing machine. The auxiliary openings 236 serve as a reservoir for processing fluid and lead to an optimum homogenization of the film of fluid on the rotor disk 224 and, indeed, on the upper and lower side and on the individual sides, and therefore also on the workpieces received in the workpiece openings 232. The rotor disk 224 shown in FIG. 3 also has a contact angle of a water drop of at least 60°. For example, the surface of the rotor disk 224 can be mechanically roughened in order to achieve said contact angle. The surface of the rotor disk 224, which can by way of example comprise of stainless steel, can, alternatively or additionally to roughening, also be provided with a coating, for example a DLC coating, in order to achieve the desired contact angle.
[0027] All or some of the rotor disks 24, 124, 224 shown in FIGS. 1-3 can include a contact angle of a water drop of preferably not more than 90°, more preferably not more than 75°. In addition, they can include a contact angle of a water drop of preferably at least 65°, more preferably at least 70°. They can, for example, be comprised of stainless steel or respectively include stainless steel as a base material during a subsequent coating. They can, however, also be comprised of other materials. It is also conceivable that the rotor disks 24, 124, 224 are comprised of a material which already intrinsically has the desired contact angle, so that no subsequent coating or roughening is required. If the surface of the rotor disks 24, 124, 224 is roughened, or if the rotor disk material already intrinsically has the desired contact angle, it is possible that these do not have any further coating.
[0028] In FIG. 4, an average workpiece thickness profile for workpieces processed with three different rotor disks, in particular silicon wafers, is depicted. The outer workpiece region as of a workpiece radius of approximately 114 mm up to the outer workpiece edge at approximately 149 mm is shown. The basic thickness in particular in the region of the workpiece middle, which can be seen in FIG. 4 for instance with the workpiece radius 114 mm, can be substantially equal or respectively standardized for all workpieces. The curves are merely depicted above one another in FIG. 4 for illustration purposes. The average workpiece thickness profiles have been established by processing in each case of a multiplicity of workpieces with one of the three rotor disks and subsequent averaging of the thickness profile. The processing was effected in the example shown in a double-sided polishing machine belonging to the applicant, wherein a polishing fluid (slurry) was fed into the working gap during the processing.
[0029] The top curve in FIG. 4 shows the average workpiece thickness profile when a plain uncoated stainless-steel rotor disk was used. The middle curve in FIG. 4 shows the average workpiece thickness profile when a stainless-steel rotor disk having a usual DLC coating was used. The bottom curve in FIG. 4 shows the average workpiece thickness profile using a rotor disk according to the invention having a contact angle of the surface for a water drop of at least 60°.
[0030] In FIG. 4, the height of the edge rounding of the workpiece thickness profiles is drawn in, in each case, for the letters A, B and C. It can be clearly seen that the edge rounding A is greatest when the stainless-steel rotor disk is used, followed by the edge rounding B when a rotor disk having a usual DLC coating is used. By contrast, a considerably lower edge rounding C is attained with the rotor disk according to the invention.
TABLE-US-00001 List of reference numerals Upper carrier disk 10 Lower carrier disk 12 Upper working disk 14 Lower working disk 16 Drive shaft 18 Drive shaft 20 Working gap 22 Rotor disk 24 Axis 26 Workpiece 28 Fluid feeding apparatus 30 Rotor disk 124 Workpiece opening 132 Outer teeth 134 Rotor disk 224 Workpiece opening 232 Outer teeth 234 Auxiliary opening 236
