JP2006021295A - Method and device for processing ultraprecise mirror surface - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method and a device for processing an ultraprecise mirror surface capable of mirror-surface processing a surface to be processed of a workpiece such as a semiconductor wafer and a substrate for a thin film without generating distortion, cracks, and thermal deterioration, etc., and suitable for mass-production. <P>SOLUTION: The surface to be processed of the workpiece K is horizontally held in a processing container W. Superfine powder adsorbing water molecules is housed in the processing container and positioned on the surface to be processed. The superfine powder is made to contact in a fluidized state with the surface to be processed of the workpiece by two-dimensionally oscillating the processing container in a horizontal surface. The mirror surface processing is made to proceed by mutual action on an interface between the superfine powder and the surface to be processed. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an ultra-precise mirror surface processing method and apparatus, and more specifically, a fine powder is fluidly contacted with a processed surface of a workpiece such as a silicon wafer, a semiconductor wafer such as SOI, and a thin film substrate, and is distorted. The present invention relates to an ultra-precise mirror surface processing method and apparatus for proceeding mirror surface processing without causing any cracks or thermal alteration.

  Conventionally, a suspension in which ultra fine powder is dispersed is flowed along the processed surface of the workpiece, and the ultra fine powder is brought into contact with the processed surface in a substantially no-load state. Ultra-precision specular machining by so-called EEM (Elastic Emission Machining) is already known, in which machining surface atoms are removed on the order of atomic units by interaction (a kind of chemical bond) at the interface between the powder and the machining surface. ing.

  In the processing using the conventional EEM, as shown in Patent Documents 1 to 3, the processing sphere is pressed against the processing surface of the workpiece and rotated by the rotation driving means so that the suspension is near the processing surface. A flow is generated, and the non-contact state is maintained with respect to the processing surface by the dynamic pressure, and the sphere is scanned over the entire processing surface, and the spot processing traces formed in the minute regions on the processing surface are continuously performed. The entire surface is processed precisely.

  However, the processing method of scanning the processing sphere and the workpiece relative to each other and making the spot processing traces continuous has the advantage that the processing surface can be processed into an arbitrary shape in an ultra-precision manner, Since the processing speed is slow, it is not suitable for uniformly mirror-finishing the entire processing surface of a workpiece such as a semiconductor wafer.

In Patent Document 4, there are a plurality of units arranged in parallel in a vertical posture with respect to the surface plate below the surface plate, each of which is rotatably supported at a fixed position by a fixed bearing, and is synchronously driven to rotate in the same direction. Are connected to the upper ends of the two shafts and the plurality of shafts at positions away from the center position, and eccentric rotation about the position away from the center position is transmitted to the surface plate. The surface plate is free from rotational motion by being rotatably fitted in a concave shape provided on the bottom surface of the panel and performing synchronous eccentric rotation in the same direction within the concave shape with the synchronous rotation of multiple axes. A drive mechanism having a plurality of eccentric discs for circular motion is disclosed.
Japanese Patent Publication No. 2-25745 Japanese Patent Publication No. 7-16870 Japanese Patent Publication No. 6-44989 Japanese Patent No. 2717124

  Therefore, in view of the above-mentioned situation, the present invention intends to solve the problem that the processed surface of a workpiece such as a semiconductor wafer and a thin film substrate is mirror-finished without causing any distortion, cracking, thermal alteration or the like. In addition, the present invention is to provide an ultra-precise mirror finishing method and apparatus suitable for mass production.

  In order to solve the above-mentioned problems, the present invention holds the processing surface of the workpiece horizontally in the processing container, and stores the ultrafine powder in which water molecules are adsorbed in the processing container. By positioning the processing vessel on the processing surface and vibrating the processing container two-dimensionally in a horizontal plane, the ultrafine powder is brought into fluid contact with the processing surface of the work piece, and the ultrafine powder and the processing surface interface with each other. An ultra-precise mirror surface processing method in which mirror surface processing is advanced by the action is configured (claim 1).

  Here, the processing container is vibrated in a circular motion without a rotational motion in a horizontal plane (Claim 2), or the processing container is rotated in a horizontal plane without a rotational motion and a linear reciprocating motion. (Claim 3) is preferable.

  Further, the present invention provides a surface plate body in which a ring-shaped weight body is fixed around a circular base body in plan view, and is disposed horizontally in a floating state with a vibration absorber supporting a portion directly below the weight body. A bearing hole is formed through the base body so that the center coincides with a vertical gland passing through the center of gravity of the surface plate body, and a drive motor is attached to the center of the lower surface of the base body so that the drive shaft can rotate to the bearing hole. And supporting a plurality of driven shafts rotatably on the base body around the drive shaft in the same rotation posture as the drive shaft, and horizontally arranging a disc-shaped vibrating body above the base body, The center of gravity of the vibrating body is rotatably supported by an eccentric drive shaft extending to the upper end of the drive shaft, and at the same time, the eccentric drive shaft is extended by an eccentric driven shaft extending to the upper end of the driven shaft. And is supported on the upper surface of the vibrator. And holding the processing surface of the workpiece horizontally in the processing container, accommodating the ultra fine powder having water molecules adsorbed in the processing container, and positioning the processing container on the processing surface. An ultra-precise mirror finishing machine was constructed in which ultra-fine powder was brought into fluid contact with the work surface of the workpiece by vibration, and mirror processing was advanced by interaction between the ultra-fine powder and the work surface interface ( Claim 4).

  Here, an air spring is used as the vibration absorber, the air spring is provided on the installation plate, and a plurality of support rods for supporting the surface plate body are installed on the installation plate when the air spring does not operate. (Claim 5).

  Further, it is more preferable that the vibrating body is disposed in a space surrounded by the base body and the ring-shaped weight body, and the vertical position of the vibrating body is set near the center of gravity of the surface plate body ( Claim 6).

  Preferably, the weight ratio of the surface plate body to the vibration body is set to 100 times or more to suppress vibration of the surface plate body so as not to give unexpected vibration to the vibration body. .

  The ultra-precision mirror surface processing method according to the first aspect of the present invention as described above is an ultrafine powder in which a processing surface of a workpiece is held horizontally in a processing container and water molecules are adsorbed in the processing container. The processing surface of a workpiece such as a semiconductor wafer and a thin film substrate is distorted, cracked, and simply placed in the processing surface by accommodating a body and vibrating the processing container two-dimensionally in a horizontal plane. It can be mirror-finished without causing any thermal alteration, and can vibrate many processing containers at the same time, which is suitable for mass production.

  According to the second aspect, uniform processing can be performed by causing the processing surface of the workpiece and the ultrafine powder to perform a circular motion and a circular motion without a relative rotational motion.

  According to the third aspect of the present invention, the processing surface of the workpiece and the ultrafine powder are moved by combining a circular motion and a linear motion with no relative rotational motion, thereby processing the workpiece. Since the relative motion between the surface and the ultrafine powder is accompanied by an acceleration motion, the processing speed can be increased.

  According to a fourth aspect of the present invention, the ultraprecision mirror surface processing apparatus holds the processing surface of the workpiece horizontally in the processing container fixed to the upper surface of the vibrator, and adsorbs water molecules in the processing container. The ultra-fine powder is accommodated and positioned on the processing surface, and the processing surface of a workpiece such as a semiconductor wafer and a thin film substrate is subjected to distortion, cracks, thermal alteration, etc. by simply vibrating the processing container. It can be mirror-finished without any occurrence, and by attaching a large number of processing containers on the upper surface of the vibrator and simultaneously vibrating a large number of processing containers, a large number of workpieces such as semiconductor wafers can be simultaneously processed. Since it can be processed, it is suitable for mass production, and further, the vibration of the vibrating body is reduced in amplitude by the large inertial mass of the surface plate body, and the surface plate body is supported in a floating state by the vibration absorber, so that the installation floor surface The transmission of vibration to can be cut off.

  According to the fifth aspect, since the surface plate body is supported by the air spring provided on the installation plate, the vibration of the vibration body is hardly transmitted to the installation floor surface, and is applied to the air spring at the time of power failure or maintenance. Even when the supply of compressed air is stopped, the entire load of the surface plate body and the vibrating body can be supported by the support rod.

  According to the sixth aspect, the vertical vibration of the vibrating body and the surface plate body can be extremely reduced, and thereby the normal direction component is reduced in the movement of the ultra fine powder with respect to the processing surface of the workpiece, so that good processing It can be carried out.

  According to the seventh aspect of the present invention, it is possible to perform excellent processing by suppressing the vibration of the surface plate body so as to prevent unexpected vibrations from being applied to the vibration body, and further reducing the vibration amplitude of the surface plate body itself. Therefore, the influence of vibration on other devices via the installation floor can be minimized.

  Next, the present invention will be described in more detail based on the embodiments shown in the accompanying drawings. FIG. 1 is an overall perspective view of an ultra-precision mirror surface processing apparatus according to the present invention, FIGS. 2 to 6 show main parts, in which K is a processing container, W is a workpiece, 1 is a surface plate, Indicates an installation plate, 3 is a vibration absorber, 4 is a drive motor, 5 is a vibration body, 6 is a base body, and 7 is a weight body.

  The ultra-precision mirror surface processing apparatus according to the present invention floats a surface plate body 1 having a large inertial mass by a plurality of vibration absorbers 3,... Arranged concentrically on an installation plate 2 installed on a floor surface. A structure in which the vibrating body 5 is vibrated by an eccentric rotation by a drive motor 4 that is supported horizontally and fixed to the surface plate body 1, and thus a processing container K that is placed on and fixed to the vibrating body 5 is vibrated. It is. Then, the processing surface of the workpiece W is held horizontally in the processing container K, and ultra fine powder having water molecules adsorbed in the processing container K is accommodated and positioned on the processing surface. By vibrating the processing container K, the ultrafine powder is brought into fluid contact with the processing surface of the workpiece W, and the mirror surface processing is advanced by the interaction between the ultrafine powder and the processing surface interface. Although the processing speed is slow, it is also possible to place a suspension obtained by dispersing ultrafine powder in ultrapure water in the processing container K and place it on the processing surface.

  More specifically, the ultra-precision mirror surface processing apparatus according to the present invention includes a surface plate body 1 in which a ring-shaped weight body 7 is fixed around a circular base body 6 in plan view, and a vibration absorber directly under the weight body 7. 3,... Are horizontally arranged in a floating state, and the base body 6 is formed with a bearing hole 8 penetrating the base body 6 so that the center coincides with a vertical gland passing through the center of gravity of the surface plate body 1. The drive motor 4 is attached to the center of the lower surface and the drive shaft 9 is rotatably supported in the bearing hole 8, and a plurality of followers are mounted on the base body 6 around the drive shaft 9 in the same rotational posture as the drive shaft 9. The shafts 10,... Are rotatably supported, the disk-like vibrating body 5 is horizontally disposed above the base body 6, and the center of gravity of the vibrating body 5 extends to the upper end of the drive shaft 9. At the same time as being rotatably supported by the drive shaft 11, the driven shaft 10 surrounds the vibrating body 5. ... eccentric driven shaft and extending to the upper end of 12, has a structure in which is rotatably supported in synchronization with the eccentric drive shaft 11 by ....

  Further, an air spring is used as the vibration absorber 3 and the air spring is provided on the installation plate 2 and the support rods 13 for supporting the surface plate body 1 when the air spring is not operated are installed. A plurality of the plates 2 are erected.

  When the vibrating body 5 is disposed in a space surrounded by the base body 6 and the ring-shaped weight body 7, and the vertical position of the vibrating body 5 is set near the center of gravity of the surface plate body 1, The longitudinal vibration of the surface plate body 1 and the vibrating body 5 can be suppressed. Furthermore, the weight ratio of the platen body 1 to the vibrating body 5 can be set to 100 times or more, so that the vibration of the surface plate body 1 can be suppressed and unexpected vibrations can be prevented from being applied to the vibrating body 5.

  Here, the processing vessel is vibrated in a circular motion without rotational motion in a horizontal plane, or the processing vessel is vibrated in combination with a circular motion without rotational motion and a linear reciprocating motion in a horizontal plane. It is preferable to do.

  Next, details of each part will be described. In the present embodiment, the surface plate body 1 is constituted by the base body 6 and the weight body 7, and the base body 6 is a disc-like shape that is fitted and fixed to the outer holding ring 14 and the inner side thereof. The weight plate 7 is connected to the upper portion of the holding ring 14 in a concavo-convex fitting state, and a ring-shaped support ring 16 is attached to the lower portion. The support ring 16 is supported by the six vibration absorbers 3 disposed on the installation plate 2. Here, the outer diameter of the weight body 7 of the surface plate body 1 is 1200 mm, the inner diameter is 820 mm, the vertical dimension is 345 mm including the weight body 7 and the support ring 16, the outer diameter of the surface plate 15 is 820 mm, and the thickness is 85 mm. It is said. As described above, the surface plate 1 is made of steel, is very heavy, and has a large size. Therefore, the platen 1 is divided into a plurality of parts in consideration of workability and handling. Further, the vibrating body 5 is made of aluminum, has an outer diameter of 800 mm, a thickness of the central portion supported by the eccentric drive shaft 11 and the eccentric driven shaft 12,... 40 mm, and a thickness of the peripheral portion side of 10 mm. The weight is reduced while maintaining rigidity.

  The inner peripheral surface of the holding ring 14 is a tapered surface 17 slightly widened upward, and the outer peripheral surface of the surface plate 15 is a tapered surface 18 slightly narrowed downward. The support ring 16 is fixed to the lower surface of the holding ring 14 from below with a bolt 19 in a state where the surface plate 15 is fitted into the holding ring 14 from above and the tapered surfaces 17 and 18 are in close contact with each other. It is attracted and fixed to the inner peripheral portion with bolts 20 from above. The weight body 7 is connected to the bolt 21 from below while being placed on the upper surface of the holding ring 14.

  As shown in FIG. 3, the drive shaft 9 passes through a bearing hole 8 formed in the center of the surface plate 15 and is rotatably supported at a fixed position by a plurality of angular bearings 22. Further, the driven shaft 10 is also rotatably supported at a fixed position by a plurality of angular bearings 24 in a bearing hole 23 formed in the radius portion of the surface plate 15. The eccentric drive shaft 11 is rotatably attached to a shaft hole 25 formed at the center of the vibrating body 5 by a plurality of angular bearings 26. The eccentric driven shaft 12 is also rotatably attached to a shaft hole 27 formed in the radius portion of the vibrating body 5 by a plurality of angular bearings 28. Here, the deviation of the center of the eccentric drive shaft 11 from the center of the drive shaft 9 is set to 5 mm in this embodiment, and the deviation of the center of the eccentric driven shaft 12 from the center of the driven shaft 10 is also set to 5 mm. It is set. Therefore, the maximum amplitude of the vibrating body 5 is 10 mm.

  The lower end of the drive shaft 9 is connected to the rotary shaft 30 of the drive motor 4 via a coupling 29. Incidentally, as the coupling 29, a magnet coupling that can connect the drive shaft 9 and the rotary shaft 30 to rotation without contact is adopted, so that the vibration of the drive motor 4 is processed through the drive shaft 9. It is prevented from being transmitted directly to the container K and thus to the workpiece W. The drive motor 4 is attached to the lower surface of the surface plate 15 via an attachment member 31 having a vibration control structure.

  As shown in FIG. 1, when an air spring is used as the vibration absorber 3, compressed air is supplied from the air pump 32 to each air spring 3 by a plurality of pressure hoses 33,. Is supported in a floating state.

When the drive shaft 9 is rotated, the eccentric drive shaft 11 rotates eccentrically, and all the eccentric driven shafts 12,... It is. Therefore, the same vibration can be applied to any position on the upper surface of the vibrator 5 regardless of the position of the processing container K. The rotational speed of the drive shaft 9 (vibration cycle of the vibrating body 5) is preferably in the range of 500 to 2000 rpm. In addition, since the super-part powder used in the present invention has a different processing speed depending on the material of the workpiece, a powder having an optimum surface property according to the workpiece should be used. For example, when the workpiece is a silicon wafer, it is preferable to use SiO ₂ or ZrO ₂ having an average particle diameter of 100 nm to 50 μm, preferably 1 μm to 10 μm. Note that the above-mentioned super-part powder is used for the surface of ultra-fine particles such as Al ₂ O ₃ and GeO ₂ that have relatively uniform particle sizes and are easily available even if they do not have uniform physical properties to the inside. It may be produced by coating a material having the above physical properties. In the apparatus according to the present embodiment, the vibration in the vertical direction of the upper surface of the vibrating body 5 has a maximum amplitude of 15 μm or less at a rotation of 1800 rpm.

  When the processing container K is vibrated in combination with a circular motion that does not involve a rotational motion and a linear reciprocating motion in a horizontal plane, a linear reciprocating device (not shown) is attached to the upper surface of the vibrating body 5. A processing container K is mounted on the. Alternatively, a rotating device is placed on the linear reciprocating device, and the circular motion and the linear reciprocating motion are combined for vibration. Further, the processing container K may be slowly rotated on the upper surface of the vibrating body 5.

Next, the results of processing the Si wafer using the above-described ultraprecision mirror surface processing apparatus are shown below. A Si wafer having a size of 50 mm × 100 mm is fixed to the bottom surface of a processing vessel K having a planar shape of 50 mm × 100 mm, and about 20 g of SiO ₂ powder on which water molecules having an average particle diameter of about 6 μm are adsorbed. This was carried out under a processing condition of 12 hours at a rotational speed of 1800 rpm of the drive shaft 9. Here, the SiO ₂ powder is put into a container whose upper surface is opened, and it is exposed to saturated water vapor that is realized by putting ultrapure water in a sealed container for 12 to 24 hours, so that water molecules are adsorbed to the SiO ₂ powder. Use it in the state where During processing, the processing container K is sealed to prevent the SiO ₂ powder from drying. It has been confirmed that when the dried SiO ₂ powder is used, the surface of the Si wafer is hardly processed.

  The result of observing the surface of the Si wafer with an atomic force microscope (AFM) before processing (FIG. 7) and after processing (FIG. 8) is shown. (A) shows the surface AFM image of the Si wafer, and (b) shows the line distribution of the surface irregularities. The PV value of the unprocessed surface in FIG. 7 was 2.397 nm and RMS was 0.213 nm, whereas the PV value of the processed surface in FIG. 8 was 1.130 nm and RMS was 0.077 nm. The excellent effect of the mirror finishing method and apparatus was confirmed. Here, the PV value represents the difference between the maximum value and the minimum value of the unevenness, and RMS represents the root mean square roughness.

It is a whole perspective view of the ultraprecision mirror surface processing apparatus of this invention. It is a longitudinal cross-sectional view similarly. It is an expanded vertical sectional view of the principal part. It is explanatory drawing which shows the planar arrangement | positioning of each component. It is a top view of the ultraprecision mirror surface processing apparatus of this invention. It is an explanatory top view which shows the mode of a vibration of a vibrating body. The surface observation result before processing of the Si wafer is shown, (a) is a surface AFM image, and (b) is a line distribution of surface irregularities. The surface observation result after processing of the Si wafer is shown, (a) shows a surface AFM image, and (b) shows a line distribution of surface irregularities.

Explanation of symbols

K processing container W work piece 1 surface plate body 2 installation plate 3 vibration absorber (air spring) 4 drive motor 5 vibration body 6 base body 7 weight body 8 bearing hole 9 drive shaft 10 driven shaft 11 eccentric drive shaft 12 eccentric driven Shaft 13 Support rod 14 Retaining ring 15 Surface plate 16 Support ring 17 Tapered surface 18 Tapered surface 19 Bolt 20 Bolt 21 Bolt 22 Angular bearing 23 Bearing hole 24 Angular bearing 25 Shaft hole 26 Angular bearing 27 Shaft hole 28 Angular bearing 29 Coupling 30 Rotating shaft 31 Mounting member 32 Air pump 33 Pressure hose

Claims (7)

  The processing surface of the workpiece is leveled and held in the processing container, and ultra fine powder having water molecules adsorbed in the processing container is accommodated and positioned on the processing surface. The ultra fine powder is fluidly contacted with the work surface of the workpiece by two-dimensional vibration in the inside, and the mirror finish is advanced by the interaction between the ultra fine powder and the work surface interface. Ultra-precision mirror finishing method.   The ultraprecision mirror surface processing method according to claim 1, wherein the processing container is vibrated by making a circular motion without a rotational motion in a horizontal plane.   The ultraprecision mirror surface processing method according to claim 1, wherein the processing container is vibrated in combination with a circular motion without a rotational motion and a linear reciprocating motion in a horizontal plane.   A surface plate body in which a ring-shaped weight body is fixed around a circular base body in a plan view is horizontally placed in a floating state with the vibration body absorbing the bottom of the weight body, and the center of gravity of the surface plate body is A bearing hole is formed in the base body so that the center coincides with the vertical gland that passes therethrough, a drive motor is attached to the center of the lower surface of the base body, and the drive shaft is rotatably supported in the bearing hole. A plurality of driven shafts are rotatably supported on the base body around the shaft in the same rotational posture as the drive shaft, and a disk-shaped vibrating body is horizontally disposed above the base body, and the position of the center of gravity of the vibrating body Is supported rotatably by an eccentric drive shaft extending to the upper end of the drive shaft, and at the same time, the periphery of the vibrating body can be rotated in synchronization with the eccentric drive shaft by an eccentric driven shaft extending to the upper end of the driven shaft. In a processing container fixed to the upper surface of the vibrating body. The processed surface of the work piece is held horizontally, and the fine powder having water molecules adsorbed in the processed container is placed on the processed surface, and the processed container is vibrated to vibrate. An ultra-precise mirror finishing apparatus characterized in that ultra fine powder is fluidly contacted with a processed surface of a workpiece, and mirror processing is advanced by interaction between the ultra fine powder and the processed surface interface.   An air spring is used as the vibration absorber, and the air spring is provided on the installation plate, and a plurality of support rods for supporting the surface plate body are provided on the installation plate when the air spring does not operate. The ultra-precision mirror surface processing apparatus according to claim 4.   The vibration body is disposed in a space surrounded by the base body and a ring-shaped weight body, and the vertical position of the vibration body is set near the center of gravity of the surface plate body. Ultra-precision mirror finishing machine. The ultra-precision mirror finishing apparatus according to any one of claims 4 to 6, wherein a weight ratio of the surface plate to the vibrating body is set to 100 times or more.

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