JP2007210074A - Grinding device, polishing device, grinding method and polishing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide grinding/polishing devices and grinding/polishing methods, which improve working precision of grinding work and polishing work, preventing occurrence of tool blinding, etc. and restraining occurrence of work failure such as chipping, cracking, etc. <P>SOLUTION: A rotation axis 33 on the side to be driven in the axial direction out of a tool rotational driving part 20 and a work holding part 15 is arranged within a driving standard surface of driving in the axial direction or in the neighborhood of it. Otherwise, supporting points 34c, 34d to support the tool rotational driving part 20 or the work holding part 15 to oscillate in a direction orthogonal with the rotation axis 33 are arranged on the both right and left sides against the rotation axis 33 of the tool rotational driving part 20 or the work holding part 15 to be oscillated. Consequently, a chin-up phenomenon of a tool is avoided and flatness is remarkably improved. Additionally, overloading and tool heating caused by it is avoided by properly controlling relative feeding of a work 13 to the tool 28 by detecting a working load. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

The present invention relates to a grinding apparatus, a polishing apparatus, a grinding method, and a polishing method for pressing a work against a rotating grindstone or pressing a work against a rotating lapping plate to finish the work surface.

A processing method is widely used in which a workpiece is pressed against a lapping surface plate including a grindstone or abrasive grains that rotate relative to the workpiece, and the workpiece surface is ground or polished to obtain a smooth finished surface (for example, Patent Documents). 1 and 2). FIG. 4A shows an example of a grinding apparatus. In the figure, a grinding apparatus 50 includes a base 51, a work spindle 53 that is rotationally driven by a motor 52 attached to the base 51, a spindle base 54 that is supported so as to be vertically movable with respect to the base 51, and a spindle The tool spindle 57 is attached to the base 54 and is driven to rotate by a motor 56.

A work holder 58 is attached to the tip of a work spindle 53 extending from below in the figure, and a work 59 such as a wafer is fixed to the work holder 58 in the illustrated example. Further, a tool holder 61 is attached to a tool spindle 57 extending from the upper side of the figure, and in the example shown in the figure, a cup-shaped (ring-shaped) grindstone 62 is fixed to face the work 59. The rotation axis of the work spindle 53 and the rotation axis of the tool spindle 57 are arranged in parallel with each other and are offset from each other.

During operation of the grinding apparatus configured as described above, both spindles 53 and 57 are driven to rotate in opposite directions. During operation, as indicated by an arrow 63, the tool spindle 57 advances toward the workpiece 59, and the grindstone 62 is pressed against the surface of the rotating workpiece 59 to grind the surface of the workpiece 59. The entire operation is controlled by a control unit (not shown). Depending on the type, the work spindle 53 may move forward with respect to the grindstone 62. Further, in the illustrated example, both the main spindles of the work spindle 53 and the tool spindle 57 indicate a vertical apparatus in which the main spindles are substantially oriented in the vertical direction, but a horizontal apparatus in which both the main spindles are substantially horizontal is also known. .

Next, FIG. 4B shows an outline of a polishing apparatus (lapping apparatus) 70 used for further polishing the workpiece surface roughness after grinding to obtain a uniform finished surface. In the figure, a polishing apparatus 70 includes a base 71, a lap surface plate 73 supported by a motor 72 attached to the base 71 so as to be rotationally driven, and a spindle supported to be movable up and down with respect to the base 71. The table 74 includes a work spindle 77 that is rotationally driven by a motor 76 attached to the spindle table 74.

A work holder 78 is attached to the tip of the work spindle 77, and a work 79 such as a wafer is attached to the work holder 78 in the illustrated example. A polishing liquid is supplied between the workpiece 79 and the lap surface plate 73 by spraying or the like from a polishing liquid supply port (not shown).

During the operation of the polishing apparatus 70 configured as described above, the lap surface plate 73 is rotationally driven by the motor 72, and similarly the work holder 78 holding the work 79 is rotationally driven by the motor 76. As the headstock 74 descends as indicated by an arrow 75, the workpiece 79 descends and is pressed against the surface of the lap surface plate 73 that rotates oppositely with a predetermined pressure. During this time, the polishing liquid is supplied from the polishing liquid supply port onto the lap surface plate 73, and the abrasive grains contained in the polishing liquid are introduced between the workpiece 79 and the lap surface plate 73, which are relatively moved, and the surface of the work 79 is polished. Is done. The entire operation is controlled by a control unit (not shown).

Some polishing apparatuses are configured in a donut shape including a portion where a lapping surface plate 73 is in contact with a workpiece 79 as shown in the figure. In addition, a method of fixing the work 79 in a non-rotating manner or rotating it freely without being forced to rotate is also seen.

A polishing liquid (slurry) used for surface polishing of the workpiece 79 is generally obtained by dispersing abrasive grains made of a hard abrasive such as diamond in an aqueous or oily polishing solution. When the polishing liquid is supplied, abrasive grains such as diamond in the polishing liquid roll between the workpiece 79 and the lap surface plate 73 or stick to the surface of the lap surface plate 73 made of a soft material such as tin or copper. The workpiece 79 on which the cutting blade appearing on the surface of the abrasive grain moves relatively is polished. Abrasive grains whose workpieces 79 have been polished and whose cutting edges have been destroyed are sequentially dropped from the surface of the lapping surface plate 73, and new abrasive grains are replenished from the supplied polishing liquid.

As apparent from the comparison between the grinding device 50 and the polishing device 70 described above, the tool spindle and its rotational drive mechanism, and the work spindle and its rotational drive mechanism are arranged facing each other so as to be parallel to each other, The configuration of the axial drive mechanism that makes the workpiece and the tool contact and separate from each other so that the workpiece and the tool can be contacted and separated is common. Accordingly, the basic configurations of both apparatuses can be formed in substantially the same manner, and both apparatuses can be configured by providing a difference between the rotation condition of the rotation drive mechanism, the load condition, or the grinding wheel mounting and the polishing liquid application.

In addition, although the spindles 57 and 77 on the side driven in the axial direction are positioned at the upper side in both devices, the spindle on the lower side can be driven up and down. In the following, for the sake of simplification of description, the spindle that is axially driven to bring the tool and the workpiece into and out of contact with each other may be referred to as an axial driving spindle, and the fixed spindle may be referred to as a fixed spindle. Which spindle is used to fix the tool or workpiece can be arbitrarily determined according to needs.
JP 2000-127003 A JP 2003-236736 A

By the way, conventionally, grinding and polishing have been mainly performed on surface finishing of structural materials such as iron, steel, and copper. On the other hand, in recent years, there are an increasing number of cases where semiconductor materials such as sapphire, silicon, and SiC, or ultra-hard materials such as ceramics (hereinafter collectively referred to as “super-hard materials”) are processed. . When grinding or polishing these hard materials, the self-generated action of the grindstone or abrasive (cutting blade regeneration action) is unlikely to occur, and tool clogging and clogging tend to occur more easily than structural materials such as steel. is there.

In addition, the superhard material as described above has specific properties such as harder, more brittle, and lower thermal conductivity than structural materials such as steel. For this reason, if clogging or clogging of the tool occurs during machining, chipping or cracking is likely to occur on the workpiece due to local heat generation, etc., so fine setting of machining conditions is required.

Furthermore, semiconductor materials and the like usually require dimensional accuracy much higher than that of structural materials, including parallelism and flatness corresponding to the final minute product. Overall, the grinding and polishing of ultra-hard materials required the development of processing techniques different from the processing of conventional structural materials. However, the conventional techniques do not always take sufficient measures. There wasn't.

For example, in the conventional grinding and polishing processes, a phenomenon of “jaw rise” is observed. This is because the grinding wheel acting while rotating with respect to the workpiece almost always contacts the workpiece from the same direction and then retracts in the opposite direction, so that the grinding wheel and the workpiece are moved in the opposite direction from the contact direction. Is a phenomenon that operates so that the mouth is relatively open. Or the phenomenon in which a tool bends with respect to a workpiece | work by the relative shift | offset | difference of the fulcrum which supports a tool spindle and the action point of the reaction force added to a tool with a process load is also included. This phenomenon is thought to be mainly due to the rigidity of the processing equipment.

FIG. 5 shows an outline of the jaw rise phenomenon. In the figure, since a machining load indicated by an arrow F is applied to the axial direction drive spindle (tool spindle) 57, the spindle 57 is centered on the mounting portion of the headstock 54 that supports the spindle 57 due to the rigidity of the apparatus. Will bend as indicated by the two-dot chain line. Further, depending on the apparatus, the entire drive side spindle 57 including the head stock 54 may swing in a direction perpendicular to the axis of the spindle 57 as indicated by an arrow R. In this case, the swing slide portion 80 is the center. Thus, further deflection can be added.

Due to the occurrence of the “upward jaw” phenomenon, there is a problem that it is difficult to ensure the desired accuracy of the parallelism and flatness of the finished surface of the workpiece. Even if the conventional structural material is not a problem, in the semiconductor material, the chin-up phenomenon caused by such deflection can be a fatal problem for the desired accuracy.

Next, in the conventional polishing process, the workpiece is generally in contact with the lapping surface with a degree of freedom. In the example shown in FIG. 6A, the work 79 is placed on the lap surface plate 73 by its own weight, and the movement is restricted by a pair of support rollers 81. When the lap surface plate 73 rotates in the direction indicated by the arrow 82, the workpiece 79 rotates as indicated by the arrow 83 due to the difference in the circumferential speed of the lap surface plate 73 in the radial direction. Is done. The work 79 is restrained at a predetermined position by the support roller 81.

In this case, the restraint in the direction facing the lap surface plate 73 of the work 79 (vertical direction in the figure) is only the weight of the work 79, and it is difficult to say that the parallelism of the work 79 with respect to the lap surface plate 73 is ensured. For this reason, it is difficult to further improve the accuracy of the parallelism and flatness of the workpiece 79 processed surface.

In the example shown in FIG. 6B, the workpiece 79 is fixed to the workpiece holder 78 and is forcibly rotated by a motor. However, since the workpiece 79 is only pivotally coupled to the tip of the workpiece holder 78 and the workpiece 79 can be tilted with respect to the lap surface plate 73, the workpiece 79 is kept parallel to the lap surface plate 73. I couldn't say. In the case of fixing the work 79 in the polishing process in the prior art, in any case, the fixing is only by this pivot coupling. For this reason, there is a limit to further improving the accuracy of the parallelism and flatness of the workpiece 79 processed surface.

Further, when the polishing process is continued in a state where the parallel relation with the workpiece 79 is not ensured, the lap surface of the lap surface plate 73 made of a soft material such as tin is unevenly worn upward or convexly downward. For this reason, there has been a problem that it is difficult to ensure the parallelism and flatness of the workpiece 79. This has been a fatal problem in processing ultra-hard materials that require particularly high precision.

As described above, the present invention improves the processing accuracy of grinding and polishing, prevents clogging and clogging of tools even when processing ultra-hard materials, and generates work defects such as chipping and cracks. An object of the present invention is to provide a grinding device, a polishing device, a grinding method, and a polishing method capable of suppressing the above.

The present invention provides a tool rotation drive unit and a work holding unit, in which the rotation axis on the side driven in the axial direction is arranged in the axial drive reference plane or in the vicinity thereof, or in a direction orthogonal to the rotation axis The support points for supporting the tool rotation driving part or the work holding part that swings in the direction of the tool rotation driving part or the work holding part to be swung on both sides of the swinging direction with respect to the rotation axis of the swinging tool rotation driving part or the work holding part This problem can be solved by arranging on both the left and right sides of the direction orthogonal to the direction, or by detecting the machining load and appropriately controlling the relative feed of the workpiece to the tool. including.

That is, a first aspect according to the present invention includes a tool rotation driving unit that rotationally drives a grinding tool or a polishing tool, and a work holding unit that holds a workpiece rotatably about a rotation axis parallel to the rotation axis of the tool. An axial direction drive unit that causes either one of the tool rotation drive unit or the work holding unit to approach or retract in the direction of both rotation axes with respect to the other, and a control unit that controls the overall operation, A grinding device or a polishing device that presses the tool against the tool to finish the plane of the workpiece, and the rotation axis of the tool rotation driving unit or the work holding unit driven by the axial direction driving unit is driven in the axial direction. The present invention relates to a grinding apparatus or a polishing apparatus that is located in a plane of a drive reference plane that guides driving by a section, or that is positioned in the vicinity of the drive reference plane.

Another aspect according to the present invention is that the tool rotation driving unit, the workpiece holding unit, the axial direction driving unit, the control unit, and any one of the tool rotation driving unit and the workpiece holding unit are rotated in both directions. A grinding device or a polishing device comprising a rocking portion that rocks in a direction orthogonal to the axis and a control unit that controls the overall operation, wherein the tool rotation driving unit or the workpiece is rocked by the rocking portion. Support points for supporting the holding unit are arranged at both front and rear positions in the swinging direction with respect to the rotating shaft of the swinging tool rotation driving unit or the workpiece holding unit, and go straight in the swinging direction. The present invention relates to a grinding apparatus or a polishing apparatus, which is disposed at both side positions of the rotation shaft in a direction to perform.

In the grinding device and the polishing device according to both the above aspects, the rigidity of the portion driven or swung in the axial direction can be increased, and an effect of avoiding a reduction in processing accuracy due to a so-called jaw lifting phenomenon is produced.

Next, still another aspect according to the present invention is to detect a machining load when machining a workpiece by the tool, in addition, a tool rotation driving unit, a workpiece holding unit, an axial driving unit, and a control unit. A grinding device or a polishing device, wherein the control unit stops or retracts the feed of the axial drive unit when a processing load detected by the detection device exceeds a certain value. The present invention also relates to a grinding apparatus or a polishing apparatus that controls to apply a predetermined feed again after the processing load returns to a predetermined value.

The detection device that detects the machining load performs machining based on a reduction in the number of rotations of the tool rotation driving unit or the workpiece holding unit while machining the rotation of the tool rotation driving unit or the workpiece holding unit with constant power. An increase in load may be detected. According to the grinding device and polishing device, when the processing load is overloaded, it is possible to detect this and control the tool feed appropriately, improving processing efficiency and avoiding work defects due to chipping, etc. Can be made possible.

Still another aspect of the present invention is a polishing apparatus that includes a tool rotation driving unit, a workpiece holding unit, an axial direction driving unit, and a control unit, wherein the workpiece holding unit is covered with the workpiece. The present invention relates to a polishing apparatus comprising a work holder that holds a machining plane so as to be parallel to the machining plane of the tool. The work holder may further include an adjustment mechanism that adjusts an attachment surface of the work holder for attaching the work to be parallel to a processing plane of the tool.

In each of the grinding apparatus and polishing apparatus described above, the control unit controls the axial drive unit to perform intermittent feed in the feed direction, or the axial drive unit moves forward and backward during spark out. Can be controlled to repeat.

Next, according to another aspect of the present invention, any one of a rotating grinding tool or a polishing tool and a workpiece is fed in the direction of the rotation axis with respect to the other, and the plane of the tool is pressed against the plane of the workpiece. A grinding method or a polishing method for flattening a plane of a workpiece, wherein a tool or a rotation axis of a workpiece driven by an axial drive portion that sends either the tool or the workpiece is fed to the axial drive portion. The present invention relates to a grinding method or a polishing method, characterized in that the grinding method or the polishing method is arranged in a plane of a driving reference plane to be guided, or arranged in the vicinity of the driving reference plane.

Further, according to another aspect of the present invention, any one of a rotating grinding tool or a polishing tool and a workpiece is fed in the direction of the rotation axis with respect to the other, and either one of the tool or the workpiece is transferred to the rotation shaft. A grinding method or a polishing method that swings in a direction orthogonal to the plane and presses the plane of the tool against the plane of the workpiece to finish the plane of the workpiece flat. A direction in which support points for supporting the rotation drive unit or the work holding unit are disposed at both front and rear positions of the rotation axis of the tool or workpiece to be swung in the swing direction, and are orthogonal to the swing direction. The present invention relates to a grinding method or a polishing method characterized by being disposed at both side positions of the rotary shaft.

According to still another aspect of the present invention, a machining load at the time of machining is detected, and when the machining load exceeds a certain value, the feed is temporarily stopped, or the feed direction is reversed. The present invention relates to a grinding method or a polishing method. Alternatively, the feed is intermittent feed, or the grinding method or the polish method is characterized by repeating forward and backward in the feed direction at the time of spark-out, and further, the tool and the workpiece at the start of machining are in contact with zero The present invention relates to a grinding method or a polishing method characterized in that a position is grasped by detecting a variation in a processing load when the position is instantaneously changed from a non-contact state. In either case, it is intended to improve machining accuracy or avoid occurrence of a workpiece defect.

According to still another aspect of the present invention, one of a rotating polishing tool and a workpiece is fed in the direction of the rotation axis with respect to the other, and the plane of the tool is pressed against the plane of the workpiece to flatten the plane of the workpiece. A polishing method for finishing, characterized in that the plane of the workpiece is held parallel to the surface of the polishing tool, and the degree of freedom of inclination of the workpiece plane with respect to the surface of the polishing tool is constrained during polishing. The present invention relates to a polishing method. This makes it possible to obtain parallelism and flatness with higher accuracy of the workpiece.

By carrying out the grinding apparatus or polishing apparatus, or the grinding method or polishing method according to the present invention, the parallelism and flatness of the workpiece can be drastically improved compared to those according to the prior art. It is possible to obtain excellent effects of suppressing the generation of cracks, improving the processing efficiency, and increasing the productivity.

A grinding apparatus and polishing apparatus, a grinding method and a polishing method according to a first embodiment of the present invention will be described with reference to the drawings. The present embodiment relates to an apparatus and a method for avoiding the “jaw rising” phenomenon of a workpiece and increasing machining accuracy. FIG. 1 shows a side view of a grinding apparatus according to the present embodiment. In the figure, the base part of the grinding apparatus shown in FIG. 4A is omitted, and only the main part is displayed. In FIG. 1, the grinding apparatus 10 includes a workpiece holding unit 15 positioned below, and a tool rotation driving unit 20 positioned above and facing the workpiece holding unit 15.

The work holding unit 15 includes a work spindle 14 that rotates a rotary table 12 via a bearing 11 by a motor attached to a base (not shown). In the illustrated example, the work 13 is fixed to the rotary table 12. . The work spindle 14 is further provided with a gear 16 and a proximity sensor 17 for detecting the rotational speed.

The tool rotation drive unit 20 includes a frame 21, a tool spindle 23 (arranged in the spindle cover 23 a), a rail 22 that guides the axial drive of the tool spindle 23, and a feed screw 24 that raises and lowers the tool spindle 23. Including. In the form shown, the work spindle 14 located below forms the fixed spindle described in the prior art, and the tool spindle 23 located above forms the same axial drive spindle. However, the vertical relationship between the fixed side and the drive side may be reversed.

The tool spindle 23 is rotationally driven by a motor 27 via a belt 26, and a grindstone 28 is attached to the lower end so as to face the workpiece 13. The feed screw 24 is driven by a motor 29 to raise and lower the tool spindle 23 via an engaging nut portion 31. Further, the tool rotation driving unit 20 according to the present embodiment includes an oscillating substrate 32 for oscillating in the left-right direction indicated by an arrow R in the figure with respect to a base (not shown).

The grinding device 10 configured as described above operates as follows. The rotary table 12 is rotated by driving a motor (not shown) of the work holding unit 15 to rotate the work 13. The rotation speed of the workpiece 13 is constantly detected by the gear 16 and the proximity sensor 17. On the other hand, in the tool rotation driving unit 20, the tool spindle 23 is rotated by driving the motor 27, the grindstone 28 is rotated, the feed screw 24 is rotated by driving the motor 29, and the tool spindle 23 is lowered. As a result, the grindstone 28 comes into contact with the workpiece 13 and starts grinding. At the same time, the entire tool rotation drive unit 20 is swung in the left-right direction in the figure via a swinging substrate 32 by a manipulator (not shown), thereby improving the processing efficiency. The overall operation is controlled by a control unit (not shown).

The grinding apparatus according to the present embodiment has the following features. First, the rail 22 for guiding the axial movement of the tool spindle 23 is arranged in alignment with the rotary shaft 33 of the tool spindle 23 in the side view shown in FIG. A pair of rails 22 is actually arranged in a direction perpendicular to the drawing, and a pair of bearings 34a and 34b are engaged with each of the pair of rails 22 to move the tool spindle 23 in the axial direction (see FIG. Up and down movement). In the present specification, a plane formed by connecting the engaging portions between the bearings 34 and the rails 22 that guide the axial movement of the tool spindle 23 is referred to as a “drive reference plane” of the tool spindle 23. To do.

In other words, in the grinding device according to the present embodiment, the rotation axis 33 of the tool spindle 23 is the drive reference plane. It will be arranged in the plane. Alternatively, the rotation shaft 33 may be disposed in the vicinity of the drive reference plane. In this case, the distance in the vicinity is preferably as short as possible, specifically, preferably within about 20 mm, and more preferably within about 10 mm.

By maintaining the relationship between the drive reference surface and the rotary shaft 33 of the tool spindle 23, the processing load applied to the grindstone 28 when processing the workpiece 13 is transmitted straight upward along the drive reference surface. The high rigidity which avoids the bending of the tool rotation drive part 20 like the prior art shown in FIG. 5, and the phenomenon of "jaw rise" by this is ensured.

Next, a pair of bearings 34 c and 34 d serving as support points for supporting the swinging substrate 32 of the tool rotation driving unit 20 with respect to the rail 25 on the base side are swinging directions (arrows) with respect to the tool spindle rotating shaft 33. It is arranged at the positions on both sides which are the front side and the rear side in the left and right direction in the figure indicated by R. In addition, a pair of rails 25 are actually arranged with the tool spindle rotating shaft 33 sandwiched in a direction perpendicular to the drawing, so that the tool spindle rotating shaft is also perpendicular to the swinging direction (direction perpendicular to the drawing). It is arranged at positions on both sides with respect to 33.

In the illustrated example, a total of four support points (bearings 34c, 34d) are arranged. However, as long as the above relationship is established, that is, the swinging direction with respect to the tool spindle rotating shaft 33, and As long as the support points are arranged at both side positions in the direction orthogonal to this, for example, the support points may be constituted by three points. At this time, it is preferable that the tool spindle rotating shaft 33 is disposed inside an envelope obtained by sequentially connecting the support points (bearings 34). By configuring the tool rotation drive unit 20 as described above, the rigidity of the apparatus with respect to the processing load is increased, and high-precision parallelism and flatness that cannot be obtained with a conventional processing apparatus can be obtained.

By swinging the tool rotation drive unit 20, the line of action of the tool with respect to the workpiece is tilted by the swing, and therefore the effect of reducing the thickness of the work-affected layer of the workpiece is reduced compared to the case where there is no swing. As a result, fine cracks are less likely to occur in the workpiece. In addition, the swinging is effective from the viewpoint of enhancing the productivity because the effect of promoting the regenerating action of the cutting blade is obtained. However, among the features according to the present embodiment, items not related to the swing mechanism can be applied as they are to a grinding apparatus and a polishing apparatus of a type not including the swing mechanism. The same applies to other embodiments described below.

Next, in the grinding apparatus according to the present embodiment shown in FIG. 1, the rotation speed of the work spindle 14 is constantly adjusted by the gear 16 attached to the work spindle 14 and the proximity sensor 17 attached to the gear 16. Detected. In general, there is a certain relationship between the electric power applied to the drive motor and the drive rotational speed of the spindle driven thereby. For this reason, when the rotation speed of the work spindle 14 driven under a constant voltage decreases during machining, it is possible to know an increase in machining load. In the present embodiment, this detection result is connected to various processing efficiency improvements and processing accuracy improvements to be described later.

Note that the features and effects of the present invention described above are not limited to the grinding apparatus that is the object of the description, and can be similarly applied to a polishing apparatus. Further, the side that is driven or swung in the axial direction does not need to be the tool rotation driving unit 20, and the work holding unit 15 may constitute the axial driving unit or may be swung. That is, it is only necessary to increase the rigidity of the entire equipment against the machining load applied to the spindle shaft driven in the axial direction.

By implementing the grinding apparatus and the polishing apparatus according to the present embodiment, a remarkable improvement effect can be obtained as compared with the apparatus according to the prior art. According to the results of experiments conducted by the inventors of the present application, the apparatus according to the present invention was used for the general flatness obtained by the apparatus according to the prior art was limited to about 300 nm with respect to the diameter of 100 mm. In some cases, it was possible to obtain a significant improvement in flatness up to 30 nm, that is, accuracy down to one order. This level of flatness has been achieved with conventional technologies, except when special processing equipment has been used so far (for example, processing of small workpieces using large equipment with a large diameter lapping plate). That was not possible.

Next, a polishing apparatus and a polishing method according to a second embodiment of the present invention will be described with reference to the drawings. FIG. 2 is an enlarged view of only the contact portion between the polishing tool and the workpiece according to the present embodiment, and the base 71 and the like shown in FIG. 4B are omitted. In FIG. 2, a tool spindle 35 extends from below, and the tool spindle 35 rotates a lap platen 36 in the direction of an arrow 37 by driving a motor (not shown). A polishing liquid (slurry) is applied to the lapping platen 36 so that the workpiece can be polished. In this specification, for convenience, the lap surface plate 36 is included in the tool, and the spindle that drives the lap surface plate 36 is referred to as a tool spindle 35.

A work spindle 38 extends from above facing the lap surface plate 36, and a work 40 is fixed to a work holder 39 at the tip thereof. In the present embodiment, the work holder 39 is constituted by a vacuum chuck, that is, the work 40 is fixedly held using a vacuum. Since the work holder 39 and the lap surface plate 36 are formed to be adjustable so as to be parallel, the work 40 fixed to the work holder 39 can always be kept parallel to the lap surface plate 36. The adjustment in the parallel direction can be performed, for example, by arranging adjustable lock bolts at four positions in the radial direction of the work holder 39.

In the polishing process in the prior art, the workpiece is placed on the lapping surface plate by its own weight as shown in FIG. 6 (a), or pivoted with respect to the workpiece holder as shown in FIG. 6 (b). It was fixed so that it could tilt. This is because the conventional polishing process is mainly aimed at improving the surface accuracy (mirror finish) of the finished surface, and the parallelism and flatness are mainly assumed by the grinding process. The same processing method has not come out in the polishing process for ultra-hard materials such as sapphire and ceramic.

According to the polishing method in the present embodiment, the workpiece 40 is fixed and held in a state parallel to the lap surface plate 36 by the workpiece holder 39 using a vacuum chuck, and therefore the inclination of the workpiece 40 is restrained, and the surface In addition to the roughness accuracy, it is possible to improve the accuracy of parallelism and flatness.

In addition, in the present embodiment, the work spindle 38 rotates as indicated by an arrow 41 to forcibly drive the work 40 at a predetermined speed, and swings in a direction perpendicular to the spindle axis as indicated by an arrow 42. It is moving. As a result, there is no variation in machining conditions in the machining process, which contributes to improvement of machining accuracy and produces an effect of improving machining efficiency.

The above configuration also produces an effect of maintaining the flatness of the processed surface of the lap surface plate 36 as well as the workpiece 40. As described above, the wrap surface plate 36 is formed of a soft material such as tin or copper in order to hold the abrasive. Therefore, when the machining of the workpiece 40 whose flatness is not maintained is repeated, the surface of the lap surface plate 36 is also unevenly worn. This uneven wear causes a vicious circle in which the flatness of the workpiece 40 is further deteriorated.

FIG. 3A shows a state of the donut-shaped lapping surface plate 36 and the workpiece 40 to be polished thereon. The workpiece 40 a shown in the upper part of the figure has a large diameter and exceeds the width W of the lap surface plate 36. In this case, even if the swing stroke is small as shown by the arrow M1, the influence on the flatness of the workpiece 40 is small. On the other hand, in the case of the work 40b having a small diameter shown in the lower part of the figure, the swing stroke is increased as shown by the arrow M2, and the edge of the lap surface plate 36 is shown as a part of the work 40b is shown by a one-dot chain line in the figure. Over the surface of the lapping plate 36 so that the processed surface of the lapping plate 36 is uniformly contacted.

FIG. 3B shows a cross section of the lap surface plate 36 taken along the line AA ′ in FIG. When the small-diameter workpiece 40b is ground without a rocking motion or with a slight rocking stroke, the surface of the lapping surface plate 36 is indicated by a broken line because it is polished around the central portion in the width direction of the lapping surface plate 36. It tends to fall into uneven wear. By holding the workpiece 40 parallel to the lap surface plate 36, forcibly rotating, and giving a sufficient swing stroke, uneven wear of the lap surface plate 36 can be avoided and flatness can be maintained. At the same time, since the polishing is performed by the flat lapping plate 36, the flatness of the workpiece 40 itself to be polished can be easily obtained.

Next, a grinding method and a polishing method according to a third embodiment of the present invention will be described. The present embodiment is directed to various aspects for further improving processing accuracy and processing efficiency. First, the first aspect relates to detecting a clogging / clogging of a tool when it is likely to occur and avoiding a processing failure associated with the clogging / clogging. In this aspect, in order to avoid a reduction in machining efficiency due to clogging or crushing or chipping of a workpiece, the machining load applied to the tool is detected, and when this exceeds a predetermined threshold, the feed of the tool is temporarily performed. Stop or retract the tool so that no further processing load is applied between the tool and the workpiece.

More specifically, the number of rotations detected by the detecting means such as the combination of the gear 16 and the proximity sensor 17 shown in FIG. 1 is always grasped, and the tool or workpiece is rotated and processed under a constant power condition. When the rotational speed falls below a certain value during this period, it is determined that an overload of the machining load that causes clogging or clogging has occurred, and the tool is retracted from the workpiece. Alternatively, at least the feeding of the tool is stopped. The rotation speed may be detected using other known methods.

In general, a cutting blade such as diamond is vulnerable to heat, and the processing capability is reduced by excessive heat generation. By retreating the tool from the workpiece, further heat generation due to overload is suppressed and the inflow of grinding fluid is promoted. As a result, a cooling effect is obtained and clogging / clogging of the tool is avoided. Processing efficiency is improved. This aspect is applicable to both grinding and polishing.

According to the results of experiments conducted by the inventors of the present application, the overload threshold is preferably 95% to 98% (98% in the case of sapphire) when the rotational speed is reduced compared to the normal rotational speed. Is detected, the tool feed is temporarily stopped or the tool is retracted from the workpiece because clogging or clogging may occur. The receding distance is preferably about 2 to 5 μm.

In the above example, the tool is moved forward (feed) / retracted, but it is only necessary that the tool and the workpiece can be moved relative to each other at the time of machining, and the work can be moved forward / backward instead of the tool. Similar effects can be obtained. The same applies to each aspect described below.

Next, the second aspect according to the present embodiment enables higher thickness accuracy management of the workpiece during spark-out, which is the final finishing stage in grinding, and obtains parallelism and flatness of the workpiece. It relates to a processing method. In the spark-out in the prior art, the feed of the tool is stopped, and the final finishing process is performed while maintaining the tool in contact with the workpiece for a certain time. However, since the problem of the overall rigidity concerning the device, the tool, and the workpiece is involved, the amount of feed of the tool and the amount of grinding by the tool do not necessarily match in grinding. For this reason, the spark-out of the prior art has a problem that it is difficult to obtain a desired thickness accuracy even if a desired surface roughness is obtained.

In this aspect, in order to avoid such a phenomenon and obtain a desired thickness, an operation (oscillation operation) of repeating the forward and backward movement of the tool during the spark out is added. By simply pressing the tool against the workpiece at a fixed position, the tool is repeatedly advanced and retracted up to a predetermined feed amount, so that the processing is close to the desired grinding amount even if the final tool feed amount is the same. Therefore, higher thickness accuracy control becomes possible.

As a preferable condition for the forward and backward movements at the time of spark-out, according to the results of experiments conducted by the inventors of the present application, for example, when surface grinding of sapphire, forward is 0.6 μm / second, backward is 2-3 μm / second, It is preferable that one cycle of forward / backward movement is 6 to 8 seconds and the number of repetitions is 15 to 20 times. In addition, although spark out is a technique generally used in grinding, the above-described oscillation operation can also be applied to polishing.

A third aspect according to this embodiment relates to sensing of a contact position between a workpiece and a tool at the moment of machining start. In order to manage the thickness accuracy, it is important to detect the processing start position. In the prior art, for example, a contact position is detected by rotating either one of a workpiece and a tool by hand and contacting both of them and sensing a sliding sound at that time. However, such an approach requires operator experience and special skills. In this aspect, as described above, the rotational speed is detected with a constant electric power for generating the rotational driving force of the workpiece or the tool, and by detecting the change in the processing load (rotational speed) at the moment when the workpiece and the tool are in contact with each other, Touch position sensing can be performed automatically. After that, by controlling the necessary feed amount of the tool on the basis of the contact position, high thickness accuracy management is possible without requiring special skills.

A fourth aspect according to the present embodiment relates to intermittent feeding that improves machining efficiency and improves machining accuracy. In conventional grinding and polishing, tools are generally processed by a constant feed except during spark-out. In this case, a machining load is continuously applied to the tool, and efficient machining cannot always be performed due to factors such as local heat generation of the cutting edge. In this aspect, the tool feed is not constant, but by intermittent feed combining feed and feed stop, heat generation of the cutting edge is suppressed, machining efficiency is increased, and chipping of the workpiece is prevented. .

According to the experiments conducted by the inventors of the present application, in the example of grinding sapphire, the intermittent feed cycle is preferably a 2-second feed and a 4-second stop, or an intermittent feed consisting of a combination of a 2-second feed and an 8-second stop. . Of course, this condition varies depending on the material of the workpiece, the tool feed amount, the tool rotation speed, and the like.

In relation to this aspect, as indicated by an arrow 41 in FIG. 2, it is preferable that the workpiece 40 is forcibly rotated through a workpiece spindle 38. When the above-described rocking motion is applied, the workpiece 40 moves in the radial direction of the lap platen 36, and therefore the peripheral speed of the lap platen 36 changes depending on the contact position, so that the workpiece 40 is in a freely rotatable state Then, the rotation of the workpiece 40 is not constant, and stable machining cannot be expected. By forcibly rotating the workpiece 40, preferable processing accuracy and surface roughness can be obtained.

A fifth aspect according to the present embodiment relates to forced cutting feed having an advantage of feeding that does not give an excessive load to the workpiece. In the prior art, for example, when polishing is performed in a state where the workpiece 40 is placed on the lap surface plate 36 by its own weight, it can be said that the feeding does not give an excessive load to the workpiece. However, with such a processing method, preferable thickness management cannot be performed. On the other hand, if processing is continued at a predetermined feed to obtain the desired thickness, the processing load increases due to clogging or clogging of the tool, and there is a risk of chipping or cracking on the workpiece due to overheating etc. There is.

In this mode, the overload of the machining load is avoided by detecting the decrease in the rotational speed of the tool or workpiece driven by the motor as described above, and in addition, a forced feed is added so that a predetermined machining amount is obtained. And In this way, if there is a possibility that the processing load may increase due to clogging or clogging, the feed amount is limited to avoid the occurrence of defects such as chipping, and forced feed is applied with the processing load reduced. A desired thickness can be obtained. That is, by combining the advantages of both overload avoidance and forced feed, it becomes possible to obtain a highly accurate product while suppressing the occurrence of defects.

By implementing any one of various processing accuracy improvement measures and defect occurrence suppression measures according to the present embodiment described above, or a combination of any of them, a significant improvement effect can be obtained over the prior art. Can do. In addition to the above-described improvement in flatness, the number of workpieces to be processed in a predetermined machining time is about several times (for example, four times). In addition, in the case of ultrathinning (thickness at the limit of polishing), the conventional technique, which was about 50 μm with respect to a diameter of 100 mm, can be combined with the various aspects of the present embodiment to have a diameter of 300 mm. To about 50 μm.

In the apparatus used in the above experiment, a dynamic pressure bearing is used instead of a general bearing for the bearing of the tool spindle, and the temperature change of the oil for generating the dynamic pressure is controlled to 1 ° C. or less. Yes. As a result, the occurrence of chattering of the main spindle that occurs when using conventional bearings is avoided, and stable spindle support is possible, thereby enabling machining of workpieces with higher accuracy.

Although various embodiments according to the present invention have been described above, it is preferable that the content of the present invention is mainly applied to semiconductor materials such as wafers and ceramics, and super hard materials. The processing technique can be applied to conventional structural materials such as steel in exactly the same way. Therefore, the subject of the present invention is not limited to the superhard material or the like that has been explained.

Further, in each of the above embodiments, the description has been made for the vertical type device in which the rotation axis of the tool spindle and the work spindle is oriented in the substantially vertical direction, but the present invention is not limited to this type. The present invention can be similarly applied to a horizontal type device in which the rotation axis is substantially horizontal.

INDUSTRIAL APPLICABILITY The present invention can be used in the industrial fields of grinding and polishing that perform surface finishing of various materials. In particular, the present invention can be applied particularly effectively when grinding and polishing ultra-hard materials such as ceramics and semiconductor wafers efficiently and with high surface accuracy.

It is a partial side view which shows the grinding apparatus of embodiment concerning this invention. It is a fragmentary perspective view which shows the grinding | polishing apparatus of other embodiment concerning this invention. It is explanatory drawing which shows the relationship between the workpiece | work grind | polished with a lapping surface plate, and a lapping surface plate. It is a side view which shows the outline | summary of the grinding apparatus (a) by a prior art, and polishing apparatus (b). It is explanatory drawing which shows the phenomenon of "jaw rise" seen in a prior art. It is a perspective view which shows the workpiece | work holding method on the lap surface plate by a prior art.

Explanation of symbols

  10. Grinding device, 12. 12. rotating table; Work, 14. Work spindle, 15. Workpiece holding unit, 16. Gears, 17. Proximity sensor, 20. Tool rotation drive unit, 22. Rails, 23. Tool spindle, 24. Feed screw, 28. Grinding wheel, 33. Tool spindle rotation axis, 34a-34d. Bearings, 35. Tool spindle, 36. Lap surface plate, 38. Work spindle, 39. Work holder, 40 workpieces, 50. Grinding device, 70. Polishing device (wrapping device).

Claims (14)

A tool rotation drive for rotating the grinding tool or polishing tool;
A workpiece holding unit that holds a workpiece rotatably about a rotation axis parallel to the rotation axis of the tool;
An axial direction drive unit that causes either one of the tool rotation drive unit or the work holding unit to approach and retract in the direction of both rotation axes with respect to the other;
A control unit that controls the overall operation, and in a grinding apparatus or a polishing apparatus that presses the workpiece against the tool to finish the plane of the workpiece,
The rotation axis of the tool rotation drive unit or workpiece holding unit driven by the axial direction drive unit is located within the plane of the drive reference plane that guides the drive by the axial direction drive unit, or the drive reference surface A grinding apparatus or a polishing apparatus characterized by being located in the vicinity of. A tool rotation drive for rotating the grinding tool or polishing tool;
A workpiece holding unit that holds a workpiece rotatably about a rotation axis parallel to the rotation axis of the tool;
An axial direction drive unit that causes either one of the tool rotation drive unit or the work holding unit to approach and retract in the direction of both rotation axes with respect to the other;
An oscillating unit that oscillates either the tool rotation driving unit or the work holding unit in a direction orthogonal to the two rotation axes;
A control unit that controls the overall operation, and in a grinding apparatus or a polishing apparatus that presses the workpiece against the tool to finish the plane of the workpiece,
The support points for supporting the tool rotation driving unit or the work holding unit swung by the rocking unit are on the front side and the rear side in the swinging direction with respect to the rotation axis of the swung tool rotation driving unit or the work holding unit. A grinding apparatus or a polishing apparatus, wherein the grinding apparatus or the polishing apparatus is disposed at both side positions of the rotating shaft in a direction perpendicular to the swing direction. A tool rotation drive for rotating the grinding tool or polishing tool;
A workpiece holding unit that holds a workpiece rotatably about a rotation axis parallel to the rotation axis of the tool;
An axial direction drive unit that causes either one of the tool rotation drive unit or the work holding unit to approach and retract in the direction of both rotation axes with respect to the other;
A detection device for detecting a processing load at the time of workpiece processing by the tool;
A control unit that controls the overall operation, and in a grinding apparatus or a polishing apparatus that presses the workpiece against the tool to finish the plane of the workpiece,
The control unit stops or reverses the feeding of the axial direction drive unit when the machining load detected by the detection device exceeds a certain value, and again returns to a predetermined value after the machining load returns to a predetermined value. A grinding apparatus or a polishing apparatus that is controlled to apply a feed.   The detection device that detects the machining load is based on a reduction in the number of rotations of the tool rotation driving unit or the work holding unit while the tool rotation driving unit or the work holding unit is rotated and processed under a constant power condition. 4. The grinding apparatus or the polishing apparatus according to claim 3, wherein an increase in processing load is detected. A tool rotation drive for rotating the grinding tool or polishing tool;
A workpiece holding unit that holds a workpiece rotatably about a rotation axis parallel to the rotation axis of the tool;
An axial direction drive unit that causes either one of the tool rotation drive unit or the work holding unit to approach and retract in the direction of both rotation axes with respect to the other;
A polishing unit that controls the overall operation, and presses the workpiece against the tool to finish the plane of the workpiece,
The said holding | maintenance part is comprised from the workpiece | work holder which hold | maintains the to-be-processed plane of the said workpiece | work so that it may become parallel to the processing plane of the said tool.   The polishing apparatus according to claim 5, further comprising an adjustment mechanism that adjusts an attachment surface of the work holder for attaching the work to be parallel to a machining plane of the tool.   The control unit controls the axial drive unit to intermittently feed in the feed direction, or controls to repeat forward and backward movement of the axial drive unit during spark out, The grinding device or the polishing device according to any one of claims 1 to 6. A grinding method or a polishing method in which any one of a rotating grinding tool or a polishing tool and a workpiece is fed in the direction of the rotation axis with respect to the other, and the plane of the tool is pressed against the plane of the workpiece to finish the plane of the workpiece flat. In
The rotation axis of the tool or workpiece driven by the axial drive unit that feeds either the tool or the workpiece is disposed within the plane of the drive reference plane that guides the feed of the axial drive unit, or the drive A grinding method or a polishing method, wherein the grinding method or the polishing method is arranged near a reference surface. Either a rotating grinding tool or a polishing tool and a workpiece are fed in the direction of the rotation axis with respect to the other, and either the tool or the workpiece is swung in a direction orthogonal to the rotation axis, In a grinding method or a polishing method in which a flat surface is pressed against a work surface to finish the work flat surface,
Support points for supporting the tool rotation driving unit or the work holding unit for swinging the tool or the work are positioned at both front and rear sides of the rotation axis of the swung tool or work in the swing direction. A grinding method or a polishing method, wherein the grinding method or the polishing method is arranged at both side positions of the rotating shaft in a direction perpendicular to the swing direction. A grinding method or a polishing method in which any one of a rotating grinding tool or a polishing tool and a workpiece is fed in the direction of the rotation axis with respect to the other, and the plane of the tool is pressed against the plane of the workpiece to finish the plane of the workpiece flat. In
A grinding method or a polishing method characterized by detecting a processing load at the time of processing, and temporarily stopping the feed when the processing load exceeds a certain value, or retreating in a direction opposite to the feed direction. . A grinding method or a polishing method in which any one of a rotating grinding tool or a polishing tool and a workpiece is fed in the direction of the rotation axis with respect to the other, and the plane of the tool is pressed against the plane of the workpiece to finish the plane of the workpiece flat. In
A grinding method or a polishing method, wherein the feed is intermittent feed, or the forward and backward movements in the feed direction are repeated during spark-out. A grinding method or a polishing method in which any one of a rotating grinding tool or a polishing tool and a workpiece is fed in the direction of the rotation axis with respect to the other, and the plane of the tool is pressed against the plane of the workpiece to finish the plane of the workpiece flat. In
Grinding method or polishing characterized by grasping a zero position where the tool and the workpiece at the start of machining contact with each other by detecting a change in machining load when changing from a non-contact state instantaneously to contact Method. In a polishing method of sending either a rotating polishing tool or a workpiece in the direction of the rotation axis with respect to the other, pressing the plane of the tool against the plane of the workpiece to finish the plane of the workpiece flat,
A polishing method characterized by holding a plane of the work so as to be parallel to a surface of the polishing tool, and restraining a degree of freedom of inclination of the work plane with respect to the surface of the polishing tool during polishing. The polishing method according to claim 13, wherein the workpiece is forcibly rotated in a machining plane.

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