JP6369263B2 - Work polishing apparatus and work manufacturing method - Google Patents

Description

  The present invention relates to a workpiece polishing apparatus and a workpiece manufacturing method, and more particularly to a workpiece polishing apparatus and a workpiece manufacturing method capable of preventing deterioration of the surface quality of the workpiece in a polishing process.

  Conventionally, in the manufacture of semiconductor wafers such as silicon wafers, which are typical examples of workpieces used for polishing, double-side polishing that simultaneously polishes the front and back surfaces of the wafer to obtain higher-precision wafer flatness quality and surface roughness quality A process is generally employed (see, for example, Patent Document 1).

  FIG. 1 is a schematic cross-sectional view of a general double-side polishing apparatus. A double-side polishing apparatus 100 shown in this figure collects a rotating surface plate 10 having an upper surface plate 11 and a lower surface plate 12 facing the upper surface plate 11, and a polishing slurry S supplied to the polishing pad 12a below the lower surface plate 12. And a receiving board 13. Polishing pads 11a and 12a are provided on the opposing surfaces of the upper surface plate 11 and the lower surface plate 12, respectively.

  The double-side polishing process of the workpiece W using this apparatus 100 is performed as follows. That is, first, the work is fitted into a holding hole of a carrier plate (not shown), and then the carrier plate is placed on the lower surface plate 12, and then the carrier plate is sandwiched between the upper surface plate 11 and the lower surface plate 12, The upper and lower surface plates and the carrier plate are relatively rotated. Thereby, both surfaces of the workpiece | work W can be mirror-polished.

  During the above-described mirror polishing of the workpiece W, the polishing slurry S is circulated between the slurry tank 14 and the double-side polishing apparatus 100. That is, the pump 15 guides the polishing slurry S from the slurry tank 14 to the upper surface plate 11 through the filter 16, and supplies the polishing slurry S from the center of the upper surface plate 11 to the surface of the workpiece W. The polished slurry S after polishing falls to the peripheral region of the receiving plate 13 and is discharged from a slurry discharge port 17 provided at the bottom of the peripheral region. Thereafter, the discharged polishing slurry S is collected, and after the pad scraps and carrier plate scraps contained in the polishing slurry S are removed by the filter 18, the polishing slurry S is returned to the slurry tank 14. Thus, the polishing slurry S circulates between the slurry tank 14 and the polishing apparatus 100.

  In general, a shielding structure is provided below the peripheral edge portion of the lower surface plate 12 to prevent the polishing slurry S from entering a rotating mechanism (not shown) existing below the center portion of the lower surface plate 12. Is. FIG. 2 is a schematic cross-sectional view of a shielding structure provided in a general double-side polishing apparatus. As shown in this figure, the lower surface plate 12 has at least two first annular walls 12b disposed concentrically on the periphery on the surface on the receiving plate 13 side. On the other hand, the receiving plate 13 has a disc-shaped bottom plate 13a having a larger diameter than the lower platen 12, and at least three third plates arranged concentrically around the periphery of the bottom plate 13a on the surface of the lower platen 12 side of the bottom plate 13a. And two annular walls 13b.

  The shielding structure L is formed by inserting and arranging at least two first annular walls 12b of the lower surface plate 12 into annular regions 21 and 22 defined by the bottom plate 13a of the receiving plate 13 and at least three second annular walls 13b. It is configured. By such a shielding structure L, it is possible to dam up the polishing slurry S that is about to enter the rotating mechanism of the lower surface plate 12, and to avoid troubles such as the bearing of the rotating mechanism being rusted or the motor being leaked. it can.

  Incidentally, in addition to the slurry discharge port 17 provided in the peripheral annular region 21 as described above, a slurry discharge port 23 for discharging the polishing slurry S that has entered the annular region 22 in the shielding structure L is separately provided. Yes. This can suppress most of the polishing slurry S that tends to enter the rotating mechanism of the lower surface plate 12 by the shielding structure L described above, but still a very small part of the polishing slurry S enters the annular region 22. . Therefore, the slurry discharge port 23 is provided in the annular region 22, and the polishing slurry S that has entered the annular region 22 is discharged.

Japanese Patent No. 3109419

It has been found that when a workpiece is polished for a long period of time using a double-side polishing apparatus having an annular structure as described above, the surface quality of the workpiece deteriorates due to contamination that was not expected at first.
SUMMARY OF THE INVENTION An object of the present invention is to propose a workpiece polishing apparatus and a workpiece manufacturing method capable of preventing deterioration of the surface quality of the workpiece in the polishing process.

  The inventor has intensively studied how to solve the above problems. For this purpose, the cause of the contamination of the workpiece was investigated in detail. As a result, in the annular structure 22 shown in FIG. 2, the adhered polishing slurry S is piled up from the bottom of the annular region 22 and reaches a height that contacts the lower portion of the first annular wall 12 b of the lower surface plate 12. found.

  The cause of the unexpected contamination is that when the lower surface plate 12 is rotated during the polishing process, the fixed polishing slurry S comes into contact with the lower portion of the first annular wall 12b of the lower surface plate 12, and the fixed polishing slurry S is fixed. This is considered to be due to the dust being scraped off to become dust, and this dust being mixed into the polishing slurry S circulating in the apparatus 100 shown in FIG. As countermeasures, it is conceivable to reduce the filter size of the filters 16 and / or 18 or to increase the number of stages of the filters 16 and / or 18. However, by reducing the filter size, the time until the filter is blocked is shortened, and the frequency of filter replacement is increased. In addition, the increase in the number of stages of filters increases the size of equipment and the amount of filter used, which makes maintenance difficult. Therefore, the present inventor diligently studied how to prevent the polishing slurry S entering the annular region 22 from being fixed.

  As described above, most of the used polishing slurry S that has fallen to the peripheral annular region 21 is blocked by the second annular wall 13 b and discharged from the slurry discharge port 17. Therefore, it is considered that the polishing slurry S entering the annular region 22 is in the form of mist or water droplets generated by the flow of the polishing slurry S or the like. Then, it is expected that such a mist-like or water-drop-like polishing slurry S enters the annular structure 22 and is repeatedly deposited and dried on the bottom and side walls of the annular structure 22.

  Considering such a sticking principle of the polishing slurry S, even if the slurry discharge port 23 in the annular region 22 is enlarged or the number of the slurry discharge ports 23 is increased, a mist-like or water-drop-like polishing slurry S is formed. It is considered that it does not function effectively in preventing sticking. Therefore, as a result of intensive investigations on how to prevent such a mist-like or water-drop-like polishing slurry S from adhering in the annular region 22 of the shielding structure L, the adhering to prevent the polishing slurry S entering the shielding structure L from adhering. It has been found that it is extremely effective to provide an anti-adhesion liquid supply means for supplying the anti-liquid into the shielding structure L, and the present invention has been completed.

That is, the gist of the present invention is as follows.
(1) a rotating surface plate having at least a lower surface plate with a polishing pad attached to the surface; and a receiving plate for collecting the polishing slurry supplied to the polishing pad below the lower surface plate; An apparatus for supplying polishing slurry to a workpiece placed on the workpiece and polishing the workpiece, and preventing the polishing slurry from entering the rotating mechanism of the lower platen between the lower platen and the receiving plate. In a workpiece polishing apparatus having a shielding structure and provided with a slurry discharge port for discharging polishing slurry that has entered the shielding structure, the polishing slurry that has entered the shielding structure is fixed. An apparatus for polishing a workpiece, comprising: an anti-adhesion liquid supply means for supplying an anti-adhesion liquid for preventing the liquid into the shielding structure.

(2) The lower surface plate has at least two first annular walls arranged concentrically around the periphery of the rotating surface plate on the surface of the receiving surface, and the surface plate is more than the lower surface plate. A disc-shaped bottom plate having a large diameter, and at least three second annular walls concentrically arranged on a peripheral surface of the bottom plate on a surface of the bottom plate on the lower surface plate side; The at least two first annular walls of the board are inserted into an annular area defined by the bottom plate of the receiving board and the at least three second annular walls, and the slurry discharge port is in the annular area. The workpiece polishing apparatus according to (1), provided.

(3) The workpiece polishing apparatus according to (1) or (2), wherein the sticking prevention liquid supply unit is provided at a position facing the slurry discharge port in the annular region.

(4) The workpiece polishing apparatus according to (2) or (3), further including a sensor that detects a liquid level of the sticking prevention liquid in the annular region.

(5) The surface according to any one of (2) to (4), wherein a surface of the bottom plate on the lower surface plate side is inclined toward the slurry discharge port side in the annular region. Polishing equipment.

(6) The workpiece polishing apparatus according to any one of (1) to (5), wherein the sticking prevention liquid is water.

(7) The workpiece polishing apparatus according to any one of (1) to (6), wherein the rotating surface plate further includes an upper surface plate.

(8) A method for manufacturing a workpiece, wherein in the workpiece polishing step, polishing is performed using the workpiece polishing apparatus according to any one of (1) to (7).

(9) The workpiece manufacturing method according to (8), wherein the workpiece is a silicon wafer cut out from a silicon ingot.

  According to the present invention, since the anti-adhesion liquid for preventing the polishing slurry that has entered the shielding structure from sticking is supplied into the shielding structure, the polishing slurry that has entered the shielding structure is prevented from sticking. Since it is possible to prevent generation of dust in the polishing slurry, it is possible to prevent deterioration of the surface quality of the workpiece in the polishing process.

It is a schematic cross section of a general double-side polishing apparatus. It is a schematic cross section of a general shielding structure provided in the polishing apparatus. It is a schematic cross section of the shielding structure provided in the workpiece | work grinding | polishing apparatus which concerns on this invention. It is a schematic cross section of the shielding structure provided in the grinding | polishing apparatus of another workpiece | work which concerns on this invention. It is a figure which shows the flowchart of an example of the manufacturing method of the workpiece | work which concerns on this invention.

(Work polishing equipment)
Hereinafter, embodiments of the present invention will be described with reference to the drawings. 1 and 2 are denoted by the same reference numerals, and description thereof is omitted. As in the polishing apparatus 100 shown in FIG. 1, the workpiece polishing apparatus according to the present invention has a rotating surface plate 10 having at least a lower surface plate 12 having a polishing pad 12 a attached to the surface, and a lower surface plate 12. And a receiving plate 13 for collecting the polishing slurry S supplied to the polishing pad 12a. Further, between the lower surface plate 12 and the receiving plate 13, there is a shielding structure L that prevents the polishing slurry S from entering the rotation mechanism (not shown) of the lower surface plate 12, and the shielding structure L A slurry discharge port 23 for discharging the intruding polishing slurry S is provided in the shielding structure L.

  Further, as shown in FIG. 2, the shielding structure L is provided with at least two first annular walls 12b concentrically arranged on the periphery on the surface of the lower surface plate 12 on the receiving plate 13 side. 13 is a disk-shaped bottom plate 13a having a diameter larger than that of the lower surface plate 12, and at least three second annular walls 13b concentrically disposed on the periphery of the bottom plate 13a on the surface of the lower surface plate 12 side of the bottom plate 13a. The at least two first annular walls 12b of the lower surface plate 12 are configured by being inserted into annular regions 21 and 22 defined by the bottom plate 13a of the receiving plate 13 and at least three second annular walls 13b. be able to.

  FIG. 3 is a schematic cross-sectional view of a shielding structure provided in the workpiece polishing apparatus according to the present invention. As shown in this figure, the workpiece polishing apparatus according to the present invention is characterized in that the anti-adhesion liquid supply means 24 is provided in the shielding structure L so that the polishing slurry S entering the annular structure 22 is fixed. It is in the point which comprised so that the sticking prevention liquid for preventing may be supplied.

  By adopting such a configuration, even when a mist-like or water-drop-like polishing slurry S enters the annular region 22, the polishing slurry S is dissolved in the anti-adhesion liquid and discharged from the slurry discharge port 23. It is possible to prevent the dust of the fixed polishing slurry S from being generated, and to prevent the surface quality of the work from being deteriorated in the polishing process.

  In the present invention, the “shielding structure” refers to an area in a range sandwiched between two of the three second annular walls 13b including the first annular wall 12b and closer to the center of the surface plate in FIG. I mean. This is the same when there are three or more first annular walls 12b and four or more second annular walls 13b.

  As the anti-adhesion liquid supplied into the annular region 22, an alkaline solution such as water, alcohol or potassium hydroxide can be used. Among them, it is preferable to use water because it has a small influence on the surrounding atmosphere and is inexpensive.

  The supply amount (flow rate) of the anti-adhesion liquid into the annular region 22 is not particularly limited as long as the mist-like or water-drop-like polishing slurry S that has entered the annular region 22 can be prevented from adhering. What is necessary is just to set suitably considering the magnitude | size of 22 and the magnitude | size of the slurry discharge port 23, etc.

  Further, the supply of the anti-adhesion liquid need not always be performed during the polishing process, and can be performed intermittently under the condition that the polishing slurry S does not adhere within the annular region 22. Thereby, the usage-amount of the sticking prevention liquid can be reduced.

  In FIG. 3, the anti-adhesion liquid supply means 24 is provided at the bottom of the annular region 22, but is not limited thereto. For example, an anti-adhesion liquid supply port (not shown) is provided at a predetermined height position of the first annular wall 12b or the second annular wall 13b, and the anti-adhesion liquid is supplied into the annular region 22 from this supply hole. It can also be configured.

  The sticking prevention liquid supply means 24 is preferably provided at a position facing the slurry discharge port 23 in the annular region 22. As a result, the polishing slurry S that has entered the annular region 22 can be dissolved in the sticking prevention liquid and discharged from the slurry discharge port 23 over the entire annular region 22.

  Moreover, it is preferable that the surface of the bottom plate 13 a constituting the receiving plate 13 on the lower surface plate 12 side is inclined toward the slurry discharge port 23 side in the annular region 22. Thereby, the sticking prevention liquid supplied into the annular region 22 can be effectively discharged from the slurry discharge port 23.

  Furthermore, as shown in FIG. 4, a sensor 25 that senses the level of the anti-sticking liquid in the annular region 22 can be provided. Thereby, it is possible to prevent the sticking prevention liquid from being excessively supplied into the annular region 22. Further, it is possible to detect in advance a trouble that the sticking prevention liquid and the polishing slurry S are not discharged from the slurry discharge port 23 for some reason.

  Note that the workpiece polishing apparatus according to the present invention is not limited to the double-side polishing apparatus shown in FIG. 1, but can be a single-wafer polishing apparatus or a chemical mechanical polishing apparatus. Needless to say.

  Thus, since the anti-adhesion liquid for preventing the polishing slurry that has entered the shielding structure from sticking is supplied into the shielding structure, the polishing slurry that has entered the shielding structure is prevented from sticking, and Since dust can be prevented from being generated, it is possible to suppress deterioration of the surface quality of the workpiece in the polishing process.

(Work manufacturing method)
Next, a method for manufacturing a workpiece according to the present invention will be described. The workpiece manufacturing method of the present invention is characterized in that in the workpiece polishing step, polishing is performed using the workpiece polishing apparatus described above. Therefore, the manufacturing conditions other than the above are not limited at all. Hereinafter, with reference to FIG. 5, a method for manufacturing a workpiece according to the present invention will be described with an example in which the workpiece is a silicon wafer.

  First, in step S1, for example, Czochralski (CZ) method is used to melt the polycrystalline silicon charged in the quartz crucible to about 1400 ° C., then immerse the seed crystal in the liquid surface and pull it up while rotating. To produce a silicon ingot. Here, in order to obtain a desired resistivity, for example, boron or phosphorus is doped. In addition, the oxygen concentration in the silicon ingot can be controlled by using a magnetic field applied Czochralski (MCZ) method in which a magnetic field is applied during manufacture of the ingot.

  Next, in step S2, after the outer periphery grinding process of the obtained silicon ingot is performed to make the diameter uniform, the silicon ingot is sliced to a thickness of about 1 mm using a wire saw or an inner peripheral cutting machine. Get a wafer.

Subsequently, in step S3, the obtained silicon wafer is transferred to a polishing apparatus, and a lapping process is performed on the silicon wafer using an alumina abrasive or the like. Thereby, the thickness of the wafer can be set to a predetermined value, and the parallelism of the front and back surfaces of the wafer can be increased.
In addition, when the polishing apparatus that performs the lapping process has a labyrinth structure and has a rotating mechanism that rotates the silicon wafer, the present invention can be applied to this polishing apparatus.

  Thereafter, in step S4, acid etching using an aqueous solution consisting of at least one of hydrofluoric acid, nitric acid, acetic acid, and phosphoric acid, or alkaline etching using an aqueous potassium hydroxide solution or an aqueous sodium hydroxide solution, or the above acid etching By using the alkali etching together, the distortion of the wafer caused by the process up to the previous process is removed.

  Subsequently, in step S5, using the workpiece polishing apparatus according to the present invention as described above, the polished silicon wafer is subjected to mirror polishing. Here, DSP processing for polishing both surfaces of the wafer is performed. That is, a silicon wafer is fitted into a carrier plate, the wafer is sandwiched between an upper surface plate 11 and a lower surface plate 12 to which a polishing cloth is attached, and a polishing slurry S such as colloidal silica is supplied between the upper and lower surface plates and the wafer. Then, the upper and lower surface plates and the carrier plate are rotated relative to each other to perform mirror polishing on both sides of the silicon wafer. Thereby, the unevenness | corrugation of a wafer surface can be reduced and a wafer with high flatness can be obtained.

  Next, in step S6, the silicon wafer that has been subjected to the double-side polishing treatment is transferred to a cleaning process. For example, SC-1 cleaning liquid that is a mixture of ammonia water, hydrogen peroxide water, and water, hydrochloric acid, hydrogen peroxide Using the SC-2 cleaning liquid that is water and a mixture of water, particles, organic substances, metals, etc. on the wafer surface are removed.

  Finally, in step S7, the cleaned silicon wafer is transferred to the inspection process, and the flatness of the wafer, the number of LPDs on the wafer surface, damage, contamination of the wafer surface, etc., as in the above-described inspection process of the present invention. Inspect. Only wafers satisfying a predetermined quality in this inspection process are shipped as products.

  In this way, it is possible to manufacture the workpiece while suppressing the deterioration of the surface quality of the workpiece in the polishing process.

  According to the present invention, since the anti-adhesion liquid for preventing the polishing slurry that has entered the shielding structure from sticking is supplied into the shielding structure, the polishing slurry that has entered the shielding structure is prevented from sticking. Since it is possible to prevent the generation of dust in the polishing slurry, it is possible to suppress the deterioration of the surface quality of the workpiece in the polishing process, which is useful for the semiconductor industry.

10 rotating surface plate 11 upper surface plate 11a, 12a polishing pad 12 lower surface plate 12b first annular wall 13 receiving plate 13a bottom plate 13b second annular wall 14 slurry tank 15 pump 16, 18 filter 17, 23 slurry discharge port 21, 22 annular Area 24 Anti-adhesion liquid supply means 25 Liquid level sensor 100 Double-side polishing apparatus L Shielding structure S Polishing slurry W Workpiece

Claims (6)

A rotating platen having at least a lower platen with a polishing pad attached to the surface; and a receiving plate for collecting the polishing slurry supplied to the polishing pad below the lower platen, and placed on the polishing pad An apparatus for polishing the workpiece by supplying polishing slurry to the workpiece, and having a shielding structure that prevents the polishing slurry from entering the rotating mechanism of the lower platen between the lower platen and the receiving plate. In the workpiece polishing apparatus, the slurry discharge port for discharging the polishing slurry that has entered into the shielding structure is provided in the shielding structure,
An anti-adhesion liquid supply means for supplying an anti-adhesion liquid for preventing the polishing slurry that has entered the shield structure from adhering to the inside of the shield structure is provided ,
The lower surface plate has at least two first annular walls arranged concentrically around the periphery of the rotating surface plate on the surface on the receiving plate side,
The receiving plate includes a disc-shaped bottom plate having a diameter larger than that of the lower platen, and at least three second annular walls arranged concentrically on the periphery of the bottom plate on a surface of the bottom plate on the lower platen side. Have
The shielding structure is formed by inserting and inserting the at least two first annular walls of the lower surface plate into an annular region defined by the bottom plate of the receiving plate and the at least three second annular walls. An outlet is provided in the annular region;
Polishing device of a work characterized by further comprising Rukoto a sensor for sensing the liquid level of the anti-sticking fluid in the annular region. Wherein the lower plate-side surface of the bottom plate is inclined toward the slurry outlet side in the annular region, the polishing device of a work according to claim 1. The anti-sticking fluid is water, the polishing device of a work according to claim 1 or 2. The rotary platen further has an upper platen, a polishing device of a work according to any one of claims 1-3. In the polishing step of the work, the manufacturing method of the work, characterized in that the polishing process is performed using the polishing device of a work according to claim 1-4. The method of manufacturing a workpiece according to claim 5 , wherein the workpiece is a silicon wafer cut out from a silicon ingot.