KR20120101371A - Device and method for the double-sided processing of flat work pieces with optimized supply of the liquid working medium - Google Patents

Abstract

The present invention relates to an apparatus for double-sided processing of a flat workpiece, the apparatus comprising an upper operating disk and a lower operating disk, wherein the operating disk between the operating surfaces of the operating disk facing each other is operated for processing the workpiece. Forming a gap, wherein at least one of the actuating disks comprises a plurality of bores extending through the actuating surface for supplying a liquid actuating medium into the actuating gap, the bores being combined into a plurality of groups and Each bore of the group is connected to a separate pressurized supply line for the working medium, and is provided with one or more pressure control devices that allow the pressure of the working medium in the supply line to be individually controlled from each other. A device for the two-sided processing of flat workpieces.

Description

DEVICE AND METHOD FOR THE DOUBLE-SIDED PROCESSING OF FLAT WORK PIECES WITH OPTIMIZED SUPPLY OF THE LIQUID WORKING MEDIUM}

The present invention relates to an apparatus for double-sided processing of a flat workpiece, the apparatus comprising an upper operating disk and a lower operating disk, wherein the operating disk between the operating surfaces of the operating disk facing each other is operated for processing the workpiece. Forming an gap, wherein at least one of the actuation disks has a plurality of bores extending through the actuation surface for feeding a liquid actuation medium into the actuation gap. will be. The invention also relates to a method for operating an apparatus for double-sided processing of a flat workpiece, said apparatus comprising an upper operating disk and a lower operating disk, said operating disk between the operating surfaces of said operating disk facing each other. Form an actuation gap for processing the workpiece, and at least one of the actuation disks has a plurality of bores extending through the actuation surface to feed a liquid actuation medium into the actuation gap; A method for operating an apparatus for processing.

Such apparatus and methods serve, for example, to double-sided polishing a semiconductor wafer. For polishing, a polishing liquid is introduced into the working gap as the actuation means. For this purpose, a two-disc polishing machine is known from document DE 100 07 390 A1. The polishing discs described in this document have a series of axis-parallel bores, the axis-parallel bores being aligned with the corresponding bores in the carrier disks supporting such polishing discs, connected to lines, and through which the polishing means Supplied to the working surface of the polishing disc. The bore is provided in the upper working disk, and the polishing means is transported downward into the polishing gap due to gravity. One problem here is that a uniform supply of polishing means into the working gap cannot always be assured. In particular, if the polishing means is depleted, an area of the polishing disc, on which the workpiece frequently travels during processing, may occur. This can affect the polishing result.

Starting from the prior art described as background, it is an object of the present invention to provide an apparatus and method of the type mentioned at the outset, wherein a sufficient supply of the working medium in the working gap is ensured at any time.

This object is in accordance with the invention that the bores are combined into several groups, each bore of each group being connected to a separate pressurized supply line for the actuating means, the pressure of the actuating means in the supply line being Equipped with one or more pressure control devices that allow them to be adjusted separately from each other, and the bores are combined into several groups, the bores of each group being pressed by the actuating means and supplied to each of the groups The pressure of the actuation means is solved by being able to be adjusted separately from each other. Preferred embodiments are found in the dependent claims, the description and the figures.

For an initially named type of device, the object of the invention is that the bores for supplying liquid are combined into several groups, each bore of each group being connected to a separate pressurized supply line for the actuating means. It is solved in that it is provided with at least one pressure control device which allows the pressure of the actuating means in the supply line to be adjusted separately from each other. For the initially named form of the method, it is an object of the present invention that the bore is combined into several groups, the bore of each group being pressed by the actuating means, and that of the actuating means supplied to each said group. The pressure is solved by being able to adjust them separately from each other.

Processing in accordance with the present invention may remove material. The device may be a device for double side polishing of a flat workpiece. The working liquid may correspondingly be a polishing liquid. However, other processing methods such as grinding or lapping may also be considered. The workpiece to be processed according to the invention, for example to be coplanar, can be a semiconductor wafer, for example. The working disk may for example be circular. The working gap is also correspondingly round. The vertical drive shaft can be connected to one or both of the working disks. If the working disks are each supported by a carrier disk, this connection can be made by the carrier disk. One or more of these drive shafts may be rotationally driven by a suitable driver such that the actuating disk connected to this drive shaft is correspondingly rotated. The workpiece is processed between working disks that rotate relative to each other. The bore is provided in at least one of the actuating disks, for example in the upper actuating disk. Naturally, such bores may also be provided on both working disks. Suitable pressure lines, for example pressure hoses or pressure pipes, which transfer the actuation means to the actuation gap may extend through the bores of the actuation disc.

According to the invention, a plurality of provided bores are divided into several groups, for example two or more groups. Pressurized feed lines are associated with each group. Thus, in the embodiments to be mentioned, a total of three or more pressurized supply lines can be provided. For example, the actuation means may be supplied by a group of bores to each particular actuation gap zone. The pressure of the actuating means is the pressure leading in the supply line or bore that is filled into the actuating means. The pressure determines the flow rate of the working fluid from the bore into the working gap. The invention makes it possible to individually control the pressure of the actuation means, and therefore the flow of the actuation means into the individual supply lines to which the actuation means is supplied, and thus into the actuation gaps for the respective groups or the respective groups of bores. Thus, the supply of actuation means, for example polishing means, can be matched to the requirements of the process in a flexible manner. The flow of the actuation means can be adjusted, for example, depending on the actuation parameters (guided by the actuation procedure). The zones or each group may be divided such that the bores of one zone are placed under substantially uniform operating conditions during operation of the device. Thus, the bores of one working gap zone can be moved at a substantially uniform frequency by the workpiece. One group of bores can be assigned to a specific radial region of the working gap, for example. Thus, the group is formed with a bore that lies in a circular zone. By means of common control of pressure and flow through the bore for the zone, the optimum supply of working fluid is ensured for the zone or for each group. In particular, the individually preset constant pressure of the actuation means can be adjusted for each supply line. Thus, although bores in different zones are placed under different operating conditions, constant polishing means supply is possible over the entire operating gap. Naturally, one or more regulating devices may be provided, for example one may be provided for each supply line or group of bores. However, it is also conceivable to have a common regulating device for regulating the pressure of the actuation means in all supply lines.

Thus, according to the present invention, it is assured that the actuation means is always supplied uniformly and sufficiently in the actuation gap. In addition to optimizing the operation results, the actuation means are also used more efficiently so that the overall requirements of the actuation means are reduced. Scratches or similar processing defects are reliably avoided. In addition, a relatively soft polishing cloth can be used. If desired, the workpiece can be cleaned through an upper operating disk with a bore, for example, in that the pressure of the actuating means increases rapidly in a short period of time. Thus, unnecessary adhesion of the workpiece while raising the upper working disk at the end of the process is reliably avoided. It is also possible to intentionally change the amount of actuation means supplied to the actuation gap, for example in order to cool the area where the processing temperature has increased. This further optimizes the operation results.

According to one particularly suitable embodiment for carrying out, the supply lines can each be connected to a common main pressure supply line and a group of bores. The main supply line is connected to the vessel of the actuating means and may have a pump, for example, which allows the working liquid to be pumped through the main supply line to a separate supply line. The pressure control circuit is then arranged in each supply line, by means of which the pressure of the actuation means can be regulated in each supply line independently of the other supply lines. It is also possible to have a flow measuring device in the supply line, wherein the measuring signal of the measuring device is connected to a corresponding flow adjusting device which regulates the liquid flow based on the measured signal of the flow measuring device. The supply line may, in a known manner, be a ring line or an annular channel, which is connected to a plurality of supply lines, for example supply tubes, which extend through the bore of the working disk. Such pressure sealing ring lines serve to supply a plurality of lines in communication with the pressure sealing ring line in a particularly simple and reliable manner. The common main pressure supply line can then be guided through a vertical drive shaft which is assigned to one or more working disks with bores. The vertical drive shaft is driven by a driver, for example a motor. Thus, the working disk connected to the drive shaft is rotated. Thus, a pressure sealed single channel rotary inlet is provided through the drive shaft for dispensing the actuation means to several different feed lines. In a preferred manner, only one main pressure supply line should be guided from the stationary machine housing to the rotating component. In this case, however, it is necessary to provide electrical control in the working disk for the distribution of the main pressure supply line to the individual supply lines. In some applications, this may not be desirable. Thus, alternatively, a multi-channel rotary inlet is also possible in which the distribution to the individual supply lines already takes place before the drive shaft and the corresponding plurality of lines are guided through the drive shaft.

According to another embodiment, the cross section of the bore or the cross section of the line of liquid guided in the bore may be reduced in the region of the end of the line open to the working surface. The cross section can be reduced by more than 50%, for example. While the actuation means flows out, such a reduction in the cross section of the area into the actuation gap causes a back pressure to be generated which ensures that the minimum pressure is maintained in the supply line even when the actuation means flows freely. In particular, there is no collapse of the pressure of the actuating means when the individual or several outlet openings are not covered. Unlike the prior art, the polishing means may not only come out of the bore without the workpiece, but rather from the bore not covered by the workpiece in principle. In particular, if the pressure in the supply line is equal to or greater than the specific operating pressure in the working gap, the outflow of liquid occurs. By maintaining a certain pressure level in the supply line, outflow from all outlet openings is assured.

Since the friction between the actuating disk and the actuating coating of the workpiece depends on the amount of liquid, a measuring device for measuring the torque applied by the rotary driver can be provided on at least one vertical shaft connected to the at least one actuating disk, The control device compares the torque measured by the measuring device with a reference torque or a reference torque range, and when there is a deviation of the measured torque from the reference torque or reference torque range, the measured torque again corresponds to the reference torque. The pressure of the actuating means in at least some of the supply lines is varied so as to be equal or within the reference torque range. The control device can also compare the measured torque with a predetermined limit torque. If the measured torque falls below the limit torque, the control device reduces the pressure of the actuating means in at least some of the supply lines such that the value of the measured torque is again above the limit torque. This design allows the torque to be applied by the driver to reach a predetermined rotational speed in the case of an excessive supply of working liquid in the working gap, dramatically reduced in a manner similar to water skiing. Naturally, the pressure can be changed in particular in all feed lines, in particular the pressure can be reduced.

The bores may be joined in groups, depending on how often the bores are covered by the workpiece to be processed during operation of the apparatus. On this basis, the more often the bore of each group is covered by the workpiece to be processed during operation of the apparatus, the higher the pressure of the actuating means in the supply line of the group can be set, respectively. Thus, for several different groups, there are several predetermined reference values for each supply line, and the reference pressure value is selected according to the expected frequency of the bore being covered by the workpiece to be processed. According to the invention, in a known manner, the carrier wheel can be equipped with one or more particularly a plurality of recesses in which the workpiece to be processed remains suspended. The carrier wheel is rotationally driven within the actuation gap, and the workpiece retained in the wheel is moved in the actuation gap along the cycloid track. This creates various possibilities for retention of the workpiece gap in the radial direction during processing of the workpiece. Thus, the likelihood of the workpiece staying in the edge region of the work gap, in particular in the inner edge, can be higher than, for example, in the center. This fact is considered by the design described above. Thus, the bores in a particular ring zone of the work gap can be joined into one group, and each ring zone is assigned a specific retention possibility for the workpiece. The greater the likelihood of stay for one ring zone or for each group, the greater the reference pressure of the actuation means for the supply lines assigned to this group. Control can be generated in such a way that the resulting distribution of the actuation means as a whole is as uniform as possible.

The method according to the invention can be carried out using the device according to the invention. The device is thus suitable for carrying out the method according to the invention.

Embodiments of the present invention are described in more detail below with reference to the drawings.

1 is a vertical sectional view of a portion of the device according to the invention.
2 is an enlarged view of a section from the view according to FIG. 1 according to a further embodiment.
3 is an enlarged view of section B from FIG. 2.
4 is a circuit diagram showing a control according to the present invention.

Like reference numerals refer to like objects unless otherwise indicated. 1 is a cross-sectional view of an apparatus 10 according to the invention for double-sided processing of a flat workpiece. The apparatus of the embodiment is a double side polishing machine for coplanar polishing of a semiconductor wafer. The device of the embodiment is shown as three supply lines 36 coming from a polishing liquid container, each of which is connected via a connecting piece 22 and a multi-channel rotary inlet 18 with a vertical drive shaft ( Guided by 20). The polishing liquid may be conveyed from the liquid container through the supply line 36 by a pump not shown in FIG. 1. The supply line 36 of the illustrated embodiment forms a respective ring line 36 with an outlet to each group of bores. Supply line 36 may be formed by a supply hose. In addition, as will be described in more detail below, a pressure regulating device, not shown, which is designed for the purpose of regulating the pressure of the actuating means in one supply line 36 may be provided.

The apparatus 10 additionally has circular upper and lower carrier disks and circular upper and lower operating disks connected to the upper and lower carrier disks, respectively, in a known manner. 1 shows only the upper carrier disk 38 and the upper actuating disk 40 connected to the upper carrier disk 38. The upper carrier disk 38 is circular in design. The apparatus 10 has a lower carrier disk and a working disk, not shown, which are generally symmetrical in design with the upper carrier disk 38 and the working disk 40. The operating disk defines a circular operating gap between the circular operating surfaces opposing each other, one of the operating surfaces of the upper operating disk 40 being shown at 46 in FIG. 1. The basic design of such a double-side polishing machine with upper and lower working disks is known, for example, from the document DE 100 07 390 A1.

As can be seen further in FIG. 1, a plurality of axial bores 48 are provided through the working disk 40, each bore 48 being aligned with a corresponding bore 50 in the upper carrier disk 38. The pressure pipes 52 extend through each bore. 1 further shows that the circular feed lines 36 are each connected to the upper opening of the pressure pipe 52.

The bores 48, 50 and respective pressure pipes 52 will be described in more detail based on the enlarged views shown in FIGS. 2 and 3. In contrast to the embodiment according to FIG. 1, in the embodiment according to FIGS. 2 and 3, a plurality of supply lines 36, bores 48, 50, and pressure pipes 52 are provided. Otherwise, the embodiments are the same. 2 and 3 show that the pressure pipe 52 is connected at its upper end to the ring line 36 via a connection 54, respectively. The pressure pipe 52 is, for example, plastic. The metal sleeve 58 is inserted into each bore 50 or 48 in the upper carrier disk 38 or the upper actuating disk 40. In the region of the pressure pipe 52, the end of the pressure pipe 52, which opens to the working surface 46, it is sealed against the sleeve 58. As can be further seen in FIG. 3, the pressure pipe 52 has at its lower end a reduction portion 62 whose cross section is reduced by more than 50%. Thus, the outlet opening of the pressure pipe 52 has a diameter significantly smaller than the main region 66 of the pressure pipe 52.

As can be seen in particular in FIGS. 1 and 2, the bores 48, 50 are located at several different radial distances to the working disk and the carrier disk. The upper actuating disk, and thus the upper carrier disk, which supports the upper actuating disk, actuates the actuating disk 40 and the carrier disk 38 at various different radial distances with respect to the central axis of rotation extending through the vertical drive shaft 20. It has a plurality of circular series of axial bores extending therethrough. The bores of radial distance are each joined in groups, and the polishing means from the ring line 36 is supplied to the bores of the radial distance.

The function of the device according to the invention will be explained in more detail using the schematic circular diagram shown in FIG. 4. The polishing means are conveyed from the vessel of the polishing means, not shown, to the supply line 36 via a check valve 70 connected to the pump 68. From there, the polishing means is further conveyed to the pressure regulating device 35. In addition, the two-way valve 72 is located in the supply line 36, respectively, to switch on and off the supply circuit supplied through the supply line 36. The pressure of the polishing means in each ring line 36 can be individually adjusted to a specific value using the pressure control device 35. In addition, a flow meter 74 is located in each supply line 36. Such regulation or flow control is known to those skilled in the art and therefore is not described here in more detail. The workpiece to be processed can be held in a carrier wheel in a known manner, for example, to be able to move along a cylindrical track in an operating gap. In the process, there are several different retention possibilities where the workpiece stays in the working gap. In particular, the different radial groups of bores in the upper actuating disk 40 are covered at various different frequencies by the workpiece during actuation. This means that, according to the present invention, the radial area of the bore that is expected to be covered more often can be pressed through the ring line 36 assigned to the bore and through the corresponding pressure regulating device 35 at a higher working pressure. Can be considered in this respect.

Claims (14)

Apparatus for the two-sided processing of flat workpieces,
An upper operating disk 40 and a lower operating disk,
Between the working surfaces 46 of the working disks facing each other, the working disks form an operating gap for processing the workpiece,
At least one of the actuation disks has a plurality of bores 48 extending through the actuation surface 46 for supplying a liquid actuation medium into the actuation gap,
The bore 48 is formed of a plurality of groups,
Each group of bores 48 is connected to a separate pressurized supply line 36 for actuation means,
One or more pressure control devices 35 are provided which allow the pressure of the actuating means in the supply line 36 to be adjusted separately from one another.
Device for double-sided processing of flat workpieces. The method of claim 1,
The supply line (36) can each be connected to a common main pressure supply line and a group of bores (48). The method of claim 2,
The common main pressure supply line is guided through a vertical drive shaft (20) assigned to one or more of the actuating disks (40) with the bore (48). The method of claim 2,
The supply line (36) is guided through a vertical drive shaft (20) assigned to one or more of the working disks (40) with the bore (48). The method according to any one of claims 1 to 4,
The cross section of the bore 48 or the cross section of the line 52 of liquid guided in the bore 48 is a flat workpiece, which becomes smaller in the end region of the line 52 opening to the working surface 46. Apparatus for double-sided processing of the substrate. The method according to any one of claims 1 to 5,
Further comprising a measuring device for measuring a torque applied by a rotary driver to one or more vertical shafts 20 connected to one or more said working disks,
The control device 35 compares the torque measured by the measuring device with a reference torque or a reference torque range, and when there is a deviation of the measured torque from the reference torque or reference torque range, the measured torque is again Varying the pressure of the actuating means in at least some of the supply lines 36 to be equal to or within a reference torque range,
Device for double-sided processing of flat workpieces. The method of claim 6,
The control device 35 compares the measured torque with a predetermined limit torque,
If the measured torque falls below the limit torque, the control device 35 reduces the pressure of the actuating means in at least some of the supply lines 36 such that the value of the measured torque is again above the limit torque,
Device for double-sided processing of flat workpieces. The method of claim 1, wherein
The bore (48) is formed in a plurality of groups according to the frequency covered by the bore (48) by the workpiece to be processed during operation of the apparatus (10). The method of claim 8,
The control device 35 operates the operation within each group of supply lines 36 depending on the frequency with which each group of bores 48 should be covered by the workpiece to be processed during operation of the device 10. Apparatus for the two-sided processing of flat workpieces, setting the pressure of the means. A method for operating an apparatus for double-sided processing of a flat workpiece,
The apparatus comprises an upper operating disk 40 and a lower operating disk,
Between the working surfaces 46 of the working disks facing each other, the working disks 40 form an operating gap for processing the workpiece,
At least one of the actuation disks has a plurality of bores 48 extending through the actuation surface 46 for supplying a liquid actuation medium into the actuation gap,
The bore 48 is formed of a plurality of groups,
The bore 48 of each group is pressed by the actuating means,
The pressure of the actuating means supplied to each group 48 can be adjusted separately from each other,
Method for operating the device for double-sided processing of flat workpieces. The method of claim 10,
The torque applied by the rotary driver to one or more vertical drive shafts 20 connected to one or more said working disks is measured,
The torque measured by the measuring device is compared with the reference torque or the reference torque range,
If there is a deviation of the measured torque from the reference torque or reference torque range, varying the pressure of the actuating means in at least several supply lines such that the measured torque is again equal to or within the reference torque range,
Method for operating the device for double-sided processing of flat workpieces. The method of claim 11,
The measured torque is compared with the predetermined limit torque
If the measured torque falls below the limit torque, reducing the pressure of the actuating means supplied to at least a few groups so that the measured torque is again above the limit torque,
Method for operating the device for double-sided processing of flat workpieces. The method according to any one of claims 10 to 12,
The bore 48 forms a plurality of groups according to the frequency with which the bore 48 should be covered by the workpiece to be processed during operation of the apparatus. . The method of claim 13,
Apparatus for two-sided processing of flat workpieces, setting the pressure of the actuating means supplied to each group according to the frequency with which each group of bores 48 should be covered by the workpiece to be processed during operation of the apparatus. How to get it working.

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