Operating method of a double-sided machining machine and double-sided machining machine

Abstract

To provide a double side processing method in which a through-put increases compared to a conventional technique even after the down time of a double side processing machine for further extended period and as a result, cost can be reduced, and to provide a double side processing machine of the type explained above.SOLUTION: In an operational method for a double side processing machine, particularly a double side polishing machine, the double side processing machine comprises upper and lower working discs (10) and (12) mutually relatively rotatable by a rotation drive unit. An operation gap (14) for processing a flat workpiece is formed between the discs (10) and (12). In a heating process before a processing process for processing the workpiece, at least the working discs (10, 12) are heated to an operation temperature by a heater (30).SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a method for operating a double-sided processing machine, particularly a double-sided polishing machine, the double-sided processing machine comprising an upper working disk and a lower working disk rotatable relative to each other by a rotational drive device, with a working gap for processing a flat workpiece being formed between the upper working disk and the lower working disk.

[0002] Furthermore, the present invention relates to a double-sided processing machine, particularly a double-sided polishing machine, the double-sided processing machine comprising an upper working disk and a lower working disk, with a working gap for processing a flat workpiece being formed between the upper working disk and the lower working disk, and the double-sided processing machine comprising a rotational drive device enabling the upper working disk and the lower working disk to be rotatable relative to each other.

Background Art

[0003] In a double-sided processing machine, such as a double-sided polishing machine, a flat workpiece, such as a semiconductor wafer, is processed, for example polished, in a working gap formed between an upper working disk and a lower working disk. During processing, the working disks rotate relative to each other by a rotational drive device. The flat workpiece can be arranged, for example, in a recess of a so-called rotor disk moving along a circular path in the working gap during processing, while rotating about the axis of the rotor disk. Thus, the workpiece is guided and processed along a cycloid orbit through the working gap. With such a double-sided processing machine, a very high surface quality, particularly a very high uniformity, of the processed workpiece is achieved. It is known that an important parameter of the processing quality is the GBIR value (Global Backside Ideal Focal Plane Range).

[0004] In particular, during material removal processing of a workpiece, a so-called slurry is often supplied to the work gap. For this reason, the upper work disc and / or lower work disc may have corresponding supply openings. Also, for example, the upper work disc and / or lower work disc may have a labyrinthine structure for flowing a coolant, such as water, during processing to maintain the work disc at a specific operating temperature during the processing step. Temperature control channel It is also known to provide a mechanism for measuring the thickness of the machined workpiece at multiple positions spaced radially apart in the work gap during the machining process, and to terminate the machining process once a specific target thickness is reached. Various sensors are known for measuring the thickness, such as eddy current sensors or optical sensors.

[0005] In practice, it has been shown that, especially in double-sided machining centers, the machining results of the first machining run performed after a long downtime are not the best. Therefore, for example, a certain GBIR value is usually not obtained until multiple machining runs have been performed, and the number of machining runs required for this appears to depend on the length of the downtime of the double-sided machining center. Until a certain quality standard is reached, workpieces machined during such machining runs will have suboptimal machining results and can therefore only be used for lower quality requirements, and in particular, they cannot be used as so-called prime wafers. Using test workpieces for the machining runs required to achieve the best machining quality can avoid defective products. However, using test workpieces reduces the throughput of the machining center and, correspondingly, increases costs. [Overview of the project] [Problems that the invention aims to solve]

[0006] Building upon the prior art described above, the object of the present invention is to provide a method that can increase throughput and consequently reduce costs compared to the prior art, even after longer downtimes of the double-sided machining equipment, and to provide a double-sided machining equipment of the type described above. [Means for solving the problem]

[0007] The present invention achieves its objectives through independent claims 1 and 9. Advantageous embodiments are disclosed in the dependent claims, specification and drawings.

[0008] In the type of method in question, the present invention achieves its objective by heating at least the work disc to the operating temperature using a heating device in a heating step prior to the machining step of processing the workpiece. In the type of double-sided machining machine in question, the present invention achieves its objective by providing a heating device for heating at least the work disc to the operating temperature in a heating step prior to the machining step of processing the workpiece.

[0009] A double-sided processing machine may be, for example, a double-sided polishing machine. However, other double-sided processing machines, such as a double-sided grinding machine or a double-sided lapping machine, are also conceivable. Each working disc may have a working cover, such as an abrasive cloth. The flat workpiece may be, for example, a semiconductor wafer. The upper working disc can be fixed to the upper support disc. Accordingly, the lower working disc can be fixed to the lower support disc. During processing of the workpiece within the working gap formed between the working discs, the working discs are rotatable relative to each other. For this purpose, a corresponding rotary drive device is provided. For example, the working discs can be driven to rotate in opposite directions to each other.

[0010] This invention is based on the knowledge that the number of machining runs required to achieve a specific machining quality is related to the temperature of the work disk, which is still quite low at the start of the run. Especially after longer periods of downtime, the work disk, and the support disk, where applicable, may have cooled to below the operating temperature. In the machining run process described in the prior art, specific machining results have been achieved by continuously heating the work disk until it reaches the operating temperature. However, as explained above, this procedure leads to reduced throughput or increased costs.

[0011] Therefore, the present invention is based on the idea of ​​providing an external heating device or external heat source, respectively, to heat at least the upper and lower working discs before the first processing step, in order to avoid the heating operation described above. The external heating device or external heat source, in this case, is provided in addition to the components of the double-sided machining machine provided for processing the workpiece, and is not formed in correspondence with the processing of the workpiece in the working gap. As described, heat is also generated during such processing, and after several heating runs, the working disc reaches the operating temperature so that the processing result meets the required criteria. However, according to the present invention, by providing a separate heating device, heating of the working disc is achieved without processing the workpiece in the working gap. In particular, during the heating step according to the present invention, no workpiece to be processed is placed in the working gap. The heating operation described above is avoided. Therefore, after the completion of the heating step, the processing step can be carried out immediately, and in the first processing run, the workpiece processed here already meets the target parameters. As a result, the throughput of the double-sided machining machine is increased and costs are reduced. The operating temperature of the upper and lower work discs is, for example, in the range of 20°C to 30°C, and is approximately 25°C.

[0012] In addition to the work disc, the support disc that holds the work disc, if provided, can also be heated to the operating temperature by the heating device. This ensures that the work disc always maintains the operating temperature.

[0013] As explained, after the heating process, one or more machining processes are performed on the workpiece in the working gap of the double-sided machining machine. The machining processes include, in particular, material removal processes on the workpiece, such as polishing, lapping, or grinding. As explained above, for this reason, multiple workpieces can be suspended in the recesses of the so-called rotor disc. The rotor disc moves, on the one hand, along a circular path through the working disc, and on the other hand, rotates around its own axis. As a result, the workpiece moves along a cycloidal trajectory through the working gap, thereby achieving the best machining results. The rotor disc can rotate, for example, on sprockets on the inner and / or outer edges of the working gap.

[0014] The heating process can be controlled or adjusted, respectively, by the control device and / or adjustment device of the double-sided machining machine, and in particular, it can be started and stopped. The adjustment device can, in particular, use the temperature of the heating source and the duration of the heating process as adjustment parameters. For example, if the work disk rotates during the heating process, the rotation speed of the work disk can also be used as an adjustment parameter. Thus, the heating process can be controlled or adjusted, respectively, by the control device and / or adjustment device.

[0015] According to one embodiment, during the heating process, the heated liquid is flowed into the working gap. The heated liquid can be, for example, water heated by a heat source. The heated liquid can have a temperature somewhat higher than the desired operating temperature, for example, 5 to 10°C higher.

[0016] In a particularly practical manner, the heated liquid can be flowed into the working gap through a supply opening for the slurry. As described above, the upper working disc and / or lower working disc may have such supply openings for supplying slurry into the working gap. Through these openings, the heated liquid can be flowed into the working gap, while ensuring that the heated liquid is distributed particularly uniformly within the working gap. The supply openings are designed, for example, as axial holes in the upper working disc and / or lower working disc.

[0017] During the heating process, the rotary drive device can rotate the work disc in the same direction, specifically in the same direction, and more specifically, at the same rotational speed. This allows for uniform heating of the work disc, particularly over its entire radial range, and, where applicable, uniform heating of the support disc, without affecting the polishing pad. However, it is possible that the work disc may remain stationary without rotating during the heating process.

[0018] During the heating process, the working discs can be held at a predetermined distance from each other by spacers between the working discs or by fixing the mounts of the upper and / or lower working discs. This achieves particularly defined effective heating of the working discs and, where applicable, the support discs. Thus, to set the working gap in a predetermined manner, the height of the upper and / or lower working discs can be set by corresponding mounts. This setting can be used according to the previous exemplary embodiment to ensure a predetermined distance between the working discs during the heating process. For example, so-called clamp shoes can be used to fix the working discs. However, it is also possible to ensure a predetermined distance between the working discs by using appropriate spacers between the working discs. For example, a spacer can be held within the gap by setting a narrower gap in the radially outer region of the working gap than in the radially inner region.

[0019] According to another embodiment, during the heating process, the upper working disc and / or lower working disc are designed Temperature control channel A heated liquid can be flowed through it. Also, as explained above, for example, the upper working disc and / or lower working disc of a double-sided machining machine, Temperature control channel It has a mechanism to prevent undesirable heating of the work disc during machining, during the machining of the workpiece. Temperature control channel Coolant, such as water, flows through it. These are designed on the upper and / or lower working discs, for example, in a maze-like structure. Temperature control channel In the embodiments described above, it can be used in the following practical ways in particular: During the heating process, instead of a coolant, a heating liquid heated in a predetermined manner is used. Temperature control channel By passing the energy through this, the heating of the work disc is effectively achieved. Naturally, the corresponding Temperature control channel It would also be possible to design the upper working disk and the upper support disk, and / or the lower working disk and the lower support disk, corresponding to the upper support disk and / or lower support disk. Temperature control channel It is also conceivable that such a design would be possible. Therefore, it is designed in this way. Temperature control channel It is also possible to flow heated liquid through it.

[0020] According to another embodiment, in the heating process, at least the work disc can be heated to the operating temperature by an electric heating device, particularly by at least one electric heating mat. Such an electric heating device, e.g., an electric heating mat, can be designed, for example, between the upper work disc and / or the lower work disc, the upper support disc and / or the lower support disc, and / or between the upper work disc and the upper support disc and / or between the lower work disc and the lower support disc. Such an electric heating device enables particularly rapid and specified heating of the work disc.

[0021] According to another embodiment, the temperature of the upper working disk and / or the lower working disk can be measured during the heating process. And after it is determined that the operating temperature has been reached by the temperature measurement, the heating process can be ended. For this purpose, for example, a temperature sensor for measuring the temperature of the upper working disk and / or the lower working disk during the heating process can be designed on the upper working disk and / or the lower working disk. When the temperature sensor detects that the operating temperature has been reached, the heating process can be ended. The heating process can thus automatically end after the temperature detected in this way has reached the operating temperature. For this reason, the temperature measurement values of the corresponding temperature sensors can be applied to the control and / or regulating device, and thus the control and / or regulation of the heating process can be based on those measurement values.

[0022] The double-sided processing machine according to the present invention can be designed to implement the method according to the present invention. Therefore, the method according to the present invention can be implemented by the double-sided processing machine according to the present invention.

[0023] Exemplary embodiments of the present invention will be described in more detail below based on the drawings.

Brief Description of the Drawings

[0024] [Figure 1] FIG. 1 shows a cross-sectional view of a double-sided processing machine according to the present invention. [Figure 2] FIG. 2 shows a chart for explaining the method according to the present invention.

Embodiments for Implementing the Invention

[0025] Unless otherwise specified, the same reference numerals indicate the same objects in the figures.

[0026] The double-sided processing machine shown in Figure 1 may be, for example, a double-sided polishing machine, and comprises an annular upper working disc 10 and a similarly annular lower working disc. An annular working gap 14 is formed between the working discs 10 and 12, within which a flat workpiece, such as a semiconductor wafer, can be processed, for example, polished. As described, the workpiece can be suspended and placed in the recess of the so-called rotor disc. The rotor disc can move along a circular path through the working gap 14, rotating about its own axis in the process. Thus, the rotor disc can rotate, for example, on a sprocket on the inner and / or outer edge of the working gap 14. This in itself is public knowledge and therefore will not be described in further detail.

[0027] The upper working disc 10 is fixed to the upper support disc 16, and the lower working disc 12 is fixed to the lower support disc 18. During machining of the workpiece in the working gap 14, the upper support disc 16 and the lower support disc 18, along with the upper working disc 10 and the lower working disc 12, rotate relative to each other around the rotation axis 20 by a rotation drive mechanism (not shown in more detail). For example, the working discs 10, 12 or the support discs 16, 18 respectively can be driven to rotate in opposite directions.

[0028] Figure 1 shows various further components of the upper and lower work disks 10 and 12. For clarity, only one of the work disks 10 and 12 is shown. It should be understood that the corresponding components described in more detail below can be designed for both work disks 10 and 12.

[0029] In the example shown, the upper working disk 10 has supply lines 22 for supplying slurry to the working gap 14. Each supply line 22 has a supply opening 23 leading to the working gap 14. Furthermore, in Figure 1, distance sensors 24, such as eddy current sensors 24, are provided on the upper working disk 10 to measure the distance to the workpiece being processed and the thickness of the workpiece at different radial positions in the working gap 14 during workpiece processing. In Figure 1, multiple temperature sensors 26 are also designed on the upper working disk 10, which measure the temperature of at least the upper working disk 10, particularly during the heating process and, for example, during the processing process. As described, temperature sensors can also be provided on the lower working disk 12. The same applies to the upper support disk 16 and the lower support disk 18. In the example shown, the measurement results from the temperature sensors 26 are applied to the control and / or adjustment device 28 of the double-sided machining machine. The control and / or adjustment device 28 controls or adjusts the operation of the double-sided machining machine, including the heating process described below.

[0030] Furthermore, the heating element 30 is schematically shown on the lower work disk 12. The heating element 30 can be, for example, an electric heating element, or for example, an electric heating mat 30. However, as will be explained below, the heating element 30 is arranged in a labyrinthine shape through which the heated liquid flows during the heating process. Temperature control channel It can be set to 30. The heating element 30 can also be designed on the upper working disk 10. The same applies to the upper support disk 16 and the lower support disk 18.

[0031] In the method according to the present invention, prior to the machining process in which a workpiece is machined in the work gap 14, the temperatures of the upper work disc 10 and the lower work disc 12 are first brought to a specific operating temperature in a heating process. The temperatures are controllable or adjustable by a control and / or adjustment device 28. For example, heated heating liquid can be flowed into the work gap 14 through a supply line 22 and a supply opening 23 in the heating process. While the heating liquid is being supplied, the work discs 10, 12 and support discs 16, 18 are rotatable within the work gap 14. During the heating process, the work discs 10, 12 can be held at a predetermined distance from each other, for example, by fixing the mounts of the upper work disc 10 and / or the lower work disc 12. A temperature sensor 26 can detect when a specific operating temperature has been reached. The control and / or adjustment device 28 can then terminate the heating process. Subsequently, the workpiece can be machined by one or more machining processes, in particular by material removal processes such as polishing, lapping, or grinding.

[0032] Alternatively or additionally, in the heating process, the heated liquid is used Temperature control channel The fluid can be passed through 30, thereby raising the temperature of the work discs 10 and 12 to a specific operating temperature. Alternatively or additionally, in the heating process, at least the work discs 10 and 12 can be heated to the operating temperature using an electric heating device 30, particularly a heating mat 30. As described above, the detection of the operating temperature and the corresponding termination of the heating process can be performed by the control and / or adjustment device 28. The control and / or adjustment device 28 can use the temperature of the supplied heating fluid, the heating output of the mechanical heating device 30, and the duration of the heating process as control and / or adjustment parameters. When the work discs 10 and 12 are rotating, the rotational speed of the work discs 10 and 12 can also be used.

[0033] Figure 2 shows the results of heating using the conventional method and heating according to the present invention. In each case, the normalized GBIR value is shown for the number of heating operations of the double-sided machining center. Curve 32 represents the case where the double-sided machining center was not operated at room temperature for 3 days and was used to machine a workpiece in the machining process without the heating process according to the present invention. It is shown that 3 heating operations were required to reach a specific GBIR value (a normalized value that should be as close to 1 as possible).

[0034] Curve 34 corresponds to curve 32 and represents the case where the double-sided machining center is left at room temperature overnight and not operated. Here, the number of heating cycles required to reach the desired GBIR value is reduced to one. However, the corresponding loss of throughput or the corresponding increase in cost is still recorded.

[0035] Curve 36 shows the results when the double-sided machining center is left at room temperature overnight without being operated, and the heating process according to the present invention is performed before the first machining process (first run). Curve 36 shows that the desired GBIR value is already obtained in the first machining run. The corresponding loss of throughput or the corresponding increase in cost was avoided. [Explanation of symbols]

[0036] 10 Upper working disk 12 Lower working disc 14. Work Gap 16 Upper support disc 18 Lower support disc 20 Rotation axis 22 supply lines 23 Supply opening 24 distance sensors 26 Temperature Sensor 28 Control and / or adjustment devices 30 Heating element 32 curve 34 curve 36 curve

Claims

1. A method for operating a double-sided machining machine, particularly a double-sided polishing machine, wherein the double-sided machining machine comprises an upper working disc (10) and a lower working disc (12) that are rotatable relative to each other by a rotary drive device, and a working gap (14) for machining a flat workpiece is formed between the upper working disc (10) and the lower working disc (12), and in a heating step prior to the machining step of machining the workpiece, at least the working discs (10, 12) are heated to an operating temperature by a heating device (30), and in the heating step, the heated liquid is flowed into the working gap (14), A method characterized in that the working discs (10, 12) rotate in the same direction of rotation by the rotary drive device during the heating process.

2. The method according to claim 1, characterized in that the heated liquid is flowed through a supply opening (23) for slurry into the working gap (14).

3. The method according to claim 1 or 2, characterized in that the working discs (10, 12) can be held at a predetermined distance from each other during the heating process by fixing a spacer between the working discs (10, 12) or the mounts of the upper and / or lower working discs (10, 12).

4. The method according to claim 1 or 2, characterized in that the heated liquid can be flowed during the heating process through temperature control channels (30) designed in the upper working disc (10) and / or lower working disc (12).

5. The method according to claim 1 or 2, characterized in that at least one of the work discs (10, 12) can be heated to an operating temperature by an electric heating device (30), particularly at least one electric heating mat (30), during the heating process.

6. The method according to claim 1 or claim 2, characterized in that the temperature of the upper working disc (10) and / or lower working disc (12) is measured during the heating process, and the heating process ends after the operating temperature is reached.

7. A double-sided machining machine, particularly a double-sided polishing machine, wherein the double-sided machining machine comprises an upper working disc (10) and a lower working disc (12), a working gap (14) for machining a flat workpiece is formed between the upper working disc (10) and the lower working disc (12), and the double-sided machining machine comprises a rotary drive device that allows the upper working disc (10) and the lower working disc (12) to rotate relative to each other, and a heating device (30) is provided for heating at least the working discs (10, 12) to an operating temperature in a heating step prior to the machining step for machining a workpiece, and in the heating step, the heated liquid is flowed into the working gap (14), A double-sided machining machine characterized in that the work discs (10, 12) rotate in the same direction of rotation by the rotary drive device during the heating process.

8. The double-sided machining machine according to claim 7, characterized in that it is designed to carry out the method described in claim 1 or claim 2.

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