JP6145548B1 - Chamfering grinding method and chamfering grinding apparatus - Google Patents

Abstract

Even in a grinding process of a notch groove, good surface roughness is realized, the burden of polishing, which is a subsequent process, is reduced, and final surface roughness and shape accuracy are improved. A chamfering grinding method for grinding an end face of a plate-like workpiece W with a grinding wheel 72, wherein the grinding wheel 72 has a groove portion 72-4 parallel to the axial direction as a processing groove 72-1, and the groove portion. The grinding wheel 72 is rotated and ultrasonic vibration is applied in the axial direction so that the machining groove 72-1 is perpendicular to the end surface of the workpiece W. Grind by pressing and pressing from the direction. [Selection] Figure 9

Description

  The present invention relates to a highly accurate chamfering grinding method and a chamfering grinding apparatus for various materials such as silicon, sapphire, a compound, and glass, in particular, end surfaces of plate-like workpieces such as semiconductor wafers and glass panels.

  In recent years, there is a strong demand for wafer quality improvement, and the processing state of the wafer end face (edge portion) is regarded as important. A semiconductor wafer such as a silicon wafer is used for manufacturing a semiconductor device or the like, but chamfering is performed by grinding an edge to prevent chipping due to handling. Further, mirror chamfering by polishing is performed as a subsequent process. In the semiconductor manufacturing process, the quality improvement of edge characteristics has become an indispensable process from wafer manufacturing to device manufacturing.

  Silicon and other materials are hard and brittle, and if the edge of the wafer remains sharp during slicing, it can easily crack or chip during handling such as transport and alignment in subsequent processing steps, and fragments can damage or contaminate the wafer surface. Or In order to prevent this, the end face of the cut wafer is chamfered with a chamfering grindstone coated with diamond. At this time, it is also necessary to match the diameters of the outer circumferences with variations, match the length of the orientation flat (OF), and match the dimensions of the minute notches called notches.

  In addition, the glass substrates used in smartphones and tablets that are designed to be thinner and lighter are masked, formed with sensor electrodes, and then cut, resulting in chamfering processing quality, processing surface roughness, The occurrence of micro cracks directly affects the end face strength of the glass substrate.

  Furthermore, in normal grinding, the chamfered portion is ground in a state where the main surface of the wafer W is perpendicular to the rotation axis of the resin grindstone. In this case, streaks due to circumferential grinding are generated in the chamfered portion. easy. Therefore, it is known to perform so-called helical grinding in which, for example, a resin grindstone is inclined with respect to the wafer to grind the chamfered portion of the wafer.

  When the helical grinding is performed, not only the processing distortion of the chamfered portion is reduced as compared with the normal grinding, but also an effect that the contact area between the chamfered portion of the wafer and the grindstone is increased and the surface roughness of the chamfered portion is improved.

  In particular, in the manufacturing process of a semiconductor device, in order to easily align the crystal orientation of a semiconductor wafer, it is essential to form a notch groove formed by cutting a part of the wafer periphery into a substantially V shape or arc shape. The substantially V-shaped notch groove is widely adopted because it can efficiently use a limited area of the wafer and has excellent positioning accuracy.

  The notch groove is a small notch provided in the peripheral portion of the wafer, and there are two main notch shapes, a U shape and a V shape. Particularly in recent years, in order to increase the yield of products, V-shaped notch grooves with less loss of wafer surface area are frequently used. The notch groove is formed by cutting the outer peripheral surface of the silicon single crystal block to a predetermined diameter with a cylindrical grinder and using a ingot cutting machine to form a V-shaped notch groove indicating the crystal orientation. And it grinds and mirror-polishs as a post process.

  Usually, the inclined surface and the end surface of the notch groove are mirror-polished using a notch polishing apparatus dedicated to the notch, since the notch groove has a shape that is significantly different from the outer periphery. The mirror surface processing of the notch groove is performed by pressing the notch groove of the wafer while rotating a polishing member composed of a disc-shaped or ring-shaped polishing cloth having a peripheral portion matched to the shape of the notch groove, For example, it is described in Patent Document 1.

  Before the notch groove is mirror-polished, it is common to perform chamfering grinding on the notch groove, and it is required to process the notch groove to an accurate dimension. Therefore, in chamfering the notch groove, in order to obtain a highly accurate V slope, a feed mechanism for moving the grindstone relatively along one V slope of the notch groove provided in the semiconductor wafer, and the grindstone as the other V of the notch groove are provided. It is known to provide a feed mechanism that relatively moves along the slope direction, and is described in Patent Document 2.

JP 2010-108968 A JP 2002-28840 A

  In the above prior art, mirror polishing is indispensable. At the time of polishing, polishing is performed while the polishing member is pressed against the notch polishing region. As shown in Patent Document 1, since the polishing member is pressed against the notch groove of the wafer while rotating, it is necessary to frequently replace the polishing member, resulting in poor working efficiency.

  Further, as shown in Patent Document 2, even if the grinding wheel is moved along the V slope of the notch groove to achieve high accuracy, if the roughness after grinding is rough, the cost of polishing in the subsequent process is high. The hanging shape was also to be destroyed.

  Furthermore, in the notch chamfering grinding in which the metal grindstone is simply rotated, the striations of the abrasive grains contained in the grindstone are transferred to the surface to be ground, and the surface finish is poor. Further, similarly to the above, cost is required for the subsequent notch polishing, and the shape is inaccurate. Therefore, it is desirable to perform helical grinding on the notch groove, but it is extremely difficult due to the shape of the notch unlike the other outer peripheral portions.

  Further, it is conceivable to use a grindstone using a resin-based resin bond for a metal grindstone, but even if the surface roughness is improved, it is not practical due to deformation of the groove shape and reduction in sharpness.

  The object of the present invention is to solve the above-mentioned problems of the prior art, and in particular, in the grinding process of the notch groove, suppress the generation of streak and realize a good surface roughness not inferior to helical grinding. Then, the burden of polishing, which is a subsequent process, is reduced, and the shape at the time of grinding is maintained even after polishing to form an accurate shape.

  In order to achieve the above object, the present invention provides a chamfering grinding method for grinding an end face of a plate-shaped workpiece with a grinding wheel rotating about a rotation axis, wherein the grinding wheel is an axis of the rotation shaft. A groove portion that is a processing groove parallel to the direction, and slopes formed above and below the groove portion, and rotates the grinding wheel and applies ultrasonic vibration in the axial direction to the end surface of the workpiece. It grinds by pressing the said processing groove from a perpendicular direction and contacting.

  Further, in the above, a chamfered notch groove is formed by pressing the processed groove in a vertical direction and contacting the end surface of the sliced V-shaped cross-sectional groove formed on the outer peripheral surface of the workpiece. Is preferred.

  Furthermore, in the above, it is preferable that the width of the processing groove is larger than the amplitude of the ultrasonic vibration with respect to the thickness of the workpiece.

  Furthermore, in the above, it is preferable that the count of the slope is larger than the count of the groove portion so that the abrasive grains become finer.

  Further, in the above, the grinding wheel is attached to a grinding spindle provided with a vibration portion for rotating the grinding wheel and applying the ultrasonic vibration to the grinding wheel, and the diameter of the grinding wheel is It is preferable that the diameter is smaller than the diameter of the vibration part.

  Further, the present invention provides a chamfering grinding apparatus for grinding an end face of a plate-shaped workpiece with a grinding wheel that rotates about a rotation axis, while rotating the grinding wheel and relative to the axial direction of the rotation axis. A grinding spindle for applying ultrasonic vibrations, the grinding wheel having a groove portion parallel to the axial direction as a processing groove, and slopes formed above and below the groove portion, and the processing groove on an end surface of the workpiece And grinding by pressing from the vertical direction.

  Furthermore, in the above, the grinding device forms a chamfered notch groove by pressing the processed groove from a vertical direction on a sliced V-shaped cross-sectional groove formed on the outer peripheral surface of the workpiece. It is preferable.

  Furthermore, in the above-described structure, it is preferable that the width of the processing groove is larger than the amplitude of the ultrasonic vibration with respect to the thickness of the workpiece.

  Furthermore, in the above, it is preferable that the count of the inclined surface is larger than the count of the groove portion so that the abrasive grains become finer.

  Further, in the above, the grinding wheel is attached to the grinding spindle provided with the vibration part for applying the ultrasonic vibration so as to be replaceable, and the diameter of the grinding wheel is made smaller than the diameter of the vibration part. Is preferred.

  According to the present invention, the grinding wheel having the groove portion parallel to the axial direction as the processing groove and the inclined surfaces formed above and below the groove portion is rotated, and the grinding is performed by applying ultrasonic vibration in the axial direction. Even in the grinding process of the notch groove, the generation of streaks can be suppressed and good surface roughness can be realized. Therefore, it is possible to reduce the burden of polishing, which is a subsequent process, and to improve the final surface roughness and shape accuracy.

The top view which shows the principal part of the notch grinding apparatus which concerns on one Embodiment of this invention. The top view which shows the structure of the process part in one Embodiment. The figure which shows the formation process of the notch groove in one Embodiment The figure which shows the detailed formation process of the notch groove in one Embodiment The perspective view which shows the grinding spindle in one Embodiment The perspective view which shows the tool holder in one Embodiment External view showing a notched grinding wheel in one embodiment The perspective view which shows the tool holder in other embodiment Sectional drawing which shows the process and shape of wafer W in one Embodiment Sectional drawing which shows the detail of the processing groove in one Embodiment The figure which shows the improvement effect in one Embodiment (surface roughness of a slope part) The figure which shows the improvement effect in one Embodiment (surface roughness of an end surface part)

  Machining the notch groove to an accurate dimension can shorten the alignment time during the fine processing of the next process, and therefore high-precision grinding is required. Embodiments of the present invention will be described below in detail with reference to the drawings. The invention is not limited to the embodiments, and constituent elements in the embodiments include those that can be easily assumed by those skilled in the art or those that are substantially the same.

  FIG. 1 is a plan view showing a main part of a chamfering apparatus having a notch grinding apparatus according to an embodiment of the present invention. The chamfering apparatus mainly includes a supply / recovery unit 20 and a processing unit 10, and includes a pre-alignment unit, a cleaning unit, a post-measurement unit, a transport unit, and the like, although not shown.

  The wafer processing step is performed in the order of slicing → chamfering → lapping → etching → donor killer → fine chamfering, and various cleanings are used to remove dirt between the processes. Silicon and other materials are hard and brittle, and if the edge of the wafer remains sharp during slicing, it can easily crack or chip during handling such as transport and alignment in subsequent processing steps, and fragments can damage or contaminate the wafer surface. Or In order to prevent this, in the chamfering process, the end surface of the cut wafer is chamfered with a chamfering grindstone coated with diamond.

  The chamfering process may be performed after the lapping process. At this time, the diameters of the outer circumferences having variations are matched, the width of the orientation flat (OF) is matched, and the size of a small notch called a notch is also matched.

  The supply / recovery unit 20 supplies the wafer W to be chamfered from the wafer cassette 30 to the processing unit 10 and collects the chamfered wafer to the wafer cassette 30. This operation is performed by the supply / recovery robot 40. The wafer cassette 30 is set on a cassette table 31 and stores a number of wafers W to be chamfered. The supply / recovery robot 40 takes out the wafers W one by one from the wafer cassette 30 and stores the chamfered wafers in the wafer cassette 30.

  The supply / recovery robot 40 includes a three-axis rotation type transfer arm 50, and the transfer arm 50 includes a suction pad (not shown) on an upper surface thereof. The transfer arm 50 holds the wafer W by vacuum suction of the back surface of the wafer W with a suction pad. In other words, the transfer arm 50 of the supply / recovery robot 40 can move up and down and turn and turn while holding the wafer W, and the wafer W is transferred by combining these operations.

  The processing unit 10 is disposed in the front portion of the wafer chamfering apparatus, and performs all processing of the outer peripheral chamfering of the wafer W, that is, roughing to finishing. The processing unit 10 includes a wafer feeding device 60, an outer peripheral grinding device 62, a transfer arm 63 that conveys the wafer W, and a notch grinding device 61. The wafer feeding device 60 has a chuck table (wafer table) 66 that holds the wafer W by suction.

  FIG. 2 is a plan view showing details of the processing unit 10, and the chuck table 66 is driven by a driving means (not shown) so that the front-rear direction (Y-axis direction), the left-right direction (X-axis direction), and the vertical direction It moves in each direction (Z-axis direction) and rotates around the central axis (θ-axis) by being driven by a chuck table drive motor (not shown).

  The peripheral grinding device 62 is disposed at a position away from the chuck table 66 by a predetermined distance in the Y-axis direction. The outer peripheral grinding device 62 has an outer peripheral spindle 68 that is driven and rotated by an outer peripheral roughing motor (not shown). The outer peripheral spindle 68 is configured to be movable in the front-rear direction (Y-axis direction) and the up-down direction (Z-axis direction) by being driven by a driving unit (not shown).

  An outer peripheral grinding wheel 69 that grinds the outer periphery of the wafer W is mounted on the outer peripheral spindle 68 and serves as a rotating shaft thereof. The outer peripheral grinding wheel 69 has a plurality of outer peripheral grinding grooves formed on the outer peripheral surface thereof (total shape grinding stone), and the outer periphery of the wafer W is ground by pressing the outer periphery of the wafer W against the groove.

  The notch grinding device 61 is disposed at a position away from the chuck table 66 by a predetermined distance in the X-axis direction. The notch grinding device 61 has a grinding spindle 71 that rotates by being driven by a notch grinding motor (not shown). The grinding spindle 71 is configured to be movable in the left-right direction (X-axis direction) and the vertical direction (Z-axis direction) by being driven by a driving means (not shown). The grinding spindle 71 is provided with a notch grinding wheel 72 for chamfering a V-shaped notch groove formed on the wafer W. Here, in FIG. 2, the notch grinding wheel 72 and the grinding spindle 71 are drawn large for easy understanding, but the actual size is small enough to grind the inside of the notch groove 1.

  The notch grinding wheel 72 has a notch grinding groove formed on the outer peripheral surface thereof (total shape grinding stone), and is chamfered and ground by pressing the notch groove formed by cutting. At this time, the notch grinding wheel 72 is rotated by the grinding spindle 71 and is subjected to grinding so that ultrasonic vibration is applied in the axial direction so that the V-shaped notch groove has a predetermined shape.

  By grinding while applying ultrasonic vibration, the movement direction of the abrasive grains intersects with the movement direction of the outer periphery of the wafer W as in the helical grinding. As a result, the contact area increases, the number of acting abrasive grains increases, the grinding due to grinding does not fall on the processing surface, etc., so that grinding wheel wear is suppressed, and the outer shape change can be reduced. .

  Further, since scratches and scratches due to scratches do not occur on the processed surface, the processed surface (grind surface) has better roughness than normal grinding. Therefore, not only grinding the notch groove but also grinding the outer peripheral grinding wheel 69 by applying ultrasonic vibration in the axial direction can provide the same effect.

  Next, details from the formation of the notch groove to the finishing process will be described. FIG. 3 is a diagram showing a process of forming the notch groove 1. The outer peripheral surface of the single crystal block 11 is shaved to a predetermined crystal diameter by a cylindrical grinder, and a V-shaped cross-sectional groove 12 or a flat surface 13 for the orientation flat 14 is formed as a notch groove 1 indicating a crystal orientation. To do.

  Next, the single crystal mass is sliced into a thin wafer having a thickness of about 1 mm in a slicing step. Thereafter, the wafer surface is transferred to a lapping process for smoothing the irregularities, and chamfering is performed to cut the corners and outer periphery of the wafer outer peripheral portion in order to prevent cracking and chipping or to adjust the size.

  Next, chemical etching (chemical polishing) for chemically treating the wafer is performed in order to remove processing distortion generated on the wafer surface layer by slicing or lapping. After the chemical etching, a heat treatment process is performed to stabilize the wafer resistance value, and the surface of the silicon single crystal wafer is polished like a mirror by mechanical chemical polishing (polishing) to obtain a final silicon single crystal wafer. It becomes.

  As described above, at a predetermined crystal orientation position in the circumferential direction of the single crystal block 11, when the single crystal block 11 is processed into the wafer W, the notch groove 1 indicating the crystal orientation is formed in the crystal main axis direction. be able to. Further, when the wafer W standard requires the provision of an orientation flat, the groove shape of the circumferential section including the V-shaped groove 12 on the outer peripheral surface of the single crystal block 11 The flat surface is processed until it disappears, and the formed flat surface can be used as the orientation flat 14.

  FIG. 4 is a diagram showing in detail the process of forming the notch groove 1 before the notch grinding process and after the notch polishing process. Before notch grinding, the shape of the notch groove 1 when the V-shaped cross-sectional groove 12 is sliced and cut remains sharp at the time of slicing as shown in the upper left figure, and is conveyed in the subsequent processing step. And easily break or chip during handling such as alignment, and the fragments can damage or contaminate the wafer surface.

  The upper right figure shows a state in which the end face of the notch groove 1 is chamfered, and the upper and lower end parts are chamfered and the V-shaped part is ground so that R is attached. The figure below shows the state after polishing after grinding. The ground end is further mirror-polished to have a rounded shape.

  Similar to the outer periphery of the wafer W, the edge of the notch groove 1 needs to be smooth and high quality, not sharp, to prevent chipping. At the same time, since it becomes a reference for aligning the crystal orientation of the semiconductor wafer, it is required that the groove shape is not deformed with an accurate dimension so as to obtain positional accuracy. On the other hand, as shown in FIG. 4, in the grinding process, the shape of the notch groove 1 can be accurately made, and further, the V slope can be made highly accurate, but it is difficult to make the surface finish sufficient. It is.

  In the polishing process, the surface finish such as the surface roughness can be improved. However, if the processing amount and the processing load are large, the groove shape is greatly deformed and the accuracy is deteriorated. Further, the polishing member is damaged, and it is necessary to damage the surface or frequently replace the polishing member. Therefore, the notch groove 1 is required to have a better surface finish by grinding.

  By simply rotating the notch chamfering grinding using a diamond-bonded metal bond grindstone, the striations of the abrasive grains contained in the grindstone are transferred to the surface to be ground, and the surface finish is poor. Notch polishing is costly, and as a result, the shape of the notch groove 1 is also inaccurate. Therefore, in the grinding process of the notch groove 1, in order to improve the shape accuracy and eliminate the generation of streak and improve the surface roughness, not only the rotation but also the helical grinding by applying vibration in the thrust direction in the notch groove 1. The same effect will be obtained.

  With reference to FIG. 5 thru | or FIG. 7, the specific example which gives the vibration to a notch groove 1 in a thrust direction and grinds is demonstrated. FIG. 5 shows a grinding spindle 71 to which a notch grinding wheel 72 is attached, FIG. 6 shows a tool holder 73, and FIG. 7 shows an appearance of the notch grinding wheel 72. The notch grinding wheel 72 is attached to the tip of the grinding spindle 71 via a tool holder 73.

  The grinding spindle 71 is provided with a bearing portion 74 and a vibration portion 75, and the vibration portion 75 is rotatably supported by the bearing portion 74. The tool holder 73 is attached to the tip of the vibration part 75 so as to be replaceable. The vibration unit 75 includes an ultrasonic transducer (not shown) and vibrates ultrasonically in the axial direction. Therefore, the notch grinding wheel 72 rotates and is subjected to ultrasonic vibration in the axial direction. The axial direction corresponds to the thickness direction of the wafer W.

  Moreover, since the vibration part 75 is provided in the grinding spindle 71, ultrasonic vibration can be effectively applied with a small amount of electric power during processing. In particular, the ultrasonic vibration can be efficiently contributed to the processing as compared with the one that ultrasonically vibrates the wafer W that is the workpiece.

  Furthermore, since the fixing of the wafer W is the same as in the prior art, the ultrasonic vibration does not elastically deform the workpiece. Further, when the wafer W side is ultrasonically vibrated, the vibration of the outer peripheral portion of the wafer W is reduced, and the impact is not received. Therefore, the shape accuracy can be improved without causing damage such as scratches on the processed surface.

The machining groove 72-1 of the notch grinding wheel 72 is formed by electric discharge machining. Further, the machining groove 72-1 has three stages of the same shape, and the groove 72-4 is parallel to the axial direction of the rotation axis of the notch grinding wheel 72 and along the rotation direction of the rotation axis. Chamfered slopes 72-2 and 72-3 for the thickness direction of the wafer W are formed on the upper and lower sides of the groove 72-4 (FIGS. 6 and 7). The notch grinding wheel 72 has a diameter of about 4 mm, a length of about 12 mm, and is smaller than the diameter D of the vibration part 75.
The groove 72-4 is pressed against the end surface of the workpiece from the vertical direction and abuts the end surface to thereby grind the end surface.

  Further, as the notch grinding grindstone 72, for example, a metal bond grindstone is used which is mainly composed of metal powder such as Fe, Cr, Cu or the like and is formed by mixing diamond abrasive grains. Since the metal bond grindstone has a strong holding power for abrasive grains, the protruding amount of abrasive grains is large, the amount of cutting per abrasive grain can be increased, and the burden of polishing processing as a subsequent process can be reduced.

  The diameter d of the tool holder 73 is made smaller than the diameter D of the vibration part 75, and the position of the step is a position where the frequency of the vibration part 75 becomes an antinode of a standing wave. The amplitude at the position of the notch grinding wheel 72 increases according to the diameter ratio D / d, and the vibration energy of the vibration part 75 is efficiently transmitted to the notch grinding wheel 72 at the tip. The tool holder 73 is a step horn type vibrator horn that resonates with the basic vibration in the longitudinal direction of the ultrasonic vibrator built in the vibration section 75 and expands the amplitude.

  FIG. 8 shows another embodiment of the tool holder 73, wherein the upper figure is a conical horn and the lower figure is an exponential horn. In consideration of the amplitude expansion rate, the stress concentration factor, and the cost, the material is selected as appropriate depending on the material of the notch grinding wheel 72, the grinding amount, and the processing accuracy. The amplitude magnifying rate is highest in the step horn type of FIG. 5, followed by the exponential horn and the conical horn, and the stress concentration factor is reversed.

  FIG. 9 shows the cross section of the wafer W to be chamfered and the shape of the machining groove 72-1 of the notch grinding wheel 72. The machining groove 72-1 includes a central groove 72-4 and slopes 72-2 and 72-3 formed above and below the groove 72-4. The groove portion 72-4 is formed vertically so that the inclined surfaces 72-2 and 72-3 have the same angle as the chamfering so that the end portion of the wafer W is not sharp.

  The angles of the inclined surfaces 72-2 and 72-3 are 3 to 55 °, preferably 5 to 45 °, and if the inclination angle is too large, the grinding resistance increases, the upper and lower corners of the end face are chipped, scratches, etc. It is not preferable. Further, the width T of the processed groove 72-1 is larger than the amplitude of the ultrasonic vibration with respect to the thickness of the wafer W. In FIG. 9, the arrow indicates that ultrasonic vibration is applied in the axial direction. When the amplitude of the ultrasonic vibration is ± 3 μm, the width T of the processed groove 72-1 is 6 μm larger than the thickness t of the wafer W. It has become.

  FIG. 10 shows the details of the machining groove 72-1, and the notch grinding wheel 72 rotates at about 3000 to 30000 rpm while ultrasonically vibrating at 30 to 50 kHz in the direction of the arrow. Therefore, the vertical groove 72-4 abuts on the wafer W at the end face of the wafer W, and the tangential force to the wafer W and the force in the vibration direction indicated by the arrow due to the rotation of the notch grinding wheel 72 are combined to advance grinding. Thereby, it becomes a fine cut by ultrasonic vibration. Further, the number of working abrasive grains is increased by the same effect as that of helical grinding, and it is possible to eliminate streaks that occur on the surface to be ground that cannot be avoided by grinding only by rotation.

  On the other hand, in the chamfered portion of the wafer W, the inclined surfaces 72-2 and 73-3 are in contact with the wafer W in the same manner, but the width T of the processing groove 72-1 is larger than the thickness of the wafer W, and therefore intermittent. Grinding. Therefore, the particle size which is the count of the slopes 72-2 and 72-3 is # 3000 to # 6000, and the particle size of the groove 72-4 is # 1500 to # 3000. Further, the grain size of the slopes 72-2 and 72-3 is made larger than the grain size of the groove portion 72-4 so that the abrasive grains become finer. The upper and lower surfaces that are intermittently ground are made uniform by setting the count of the notch grinding wheel 72 higher than that of the center surface.

  The notch grinding wheel 72 includes a chamfering grindstone material having a porous surface containing a lubricant together with a saturated fatty acid solution, and the surface is dried to form a lubricant-impregnated grindstone. The grindstone containing this lubricant is water-cooled during grinding. It is desirable to use. Thereby, the lubricant can be reliably supplied to the cutting point of the grindstone, and the cutting point temperature can be set to a predetermined temperature or lower.

  Further, in order to increase the width of the machining groove 72-1, it is processed in advance by electric discharge machining.

  As described above, by rotating the notch grinding wheel 72 with respect to the wafer W and applying ultrasonic vibration, the movement direction of the abrasive grains intersects with the movement direction of the wafer W, and the processing groove 72-1 By making the width wider than the workpiece, the same effect can be obtained by applying helical grinding to chamfering. Thereby, the surface roughness of the end face and the processing distortion are reduced, and even a high count grindstone can be used for a long time.

  An example of the improvement effect when this embodiment is applied is shown in FIGS. FIG. 11 is a photomicrograph showing the surface roughness of the chamfered slope portion, and FIG. 12 is a photomicrograph showing the surface roughness of the end surface portion. Grinding process with only ultrasonic wave, and the left figure shows grinding process with ultrasonic vibration.

  In the slope portion in FIG. 11, the grinding of the chamfered portion of the wafer W is intermittently ground in the vertical direction by ultrasonic vibration, and chips are generated in small increments. Further, the lubrication state is improved at the interface where the notch grinding wheel 72 and the wafer W are in contact with each other, and the friction reduction effect, the grinding surface cleaning, and the discharge of grinding waste are promoted. Thereby, the original cutting ability and the vibration acceleration motion of the abrasive grains are added, the cutting resistance is reduced, and the grinding performance is improved.

  In FIG. 11, the count of the notch grinding wheel 72 is set to # 3000. However, the surface roughness of the surface roughness of 1.1 μm by the grinding process by only rotating is 0.1 μm and the surface roughness is 0. It was 5 μm, and an improvement effect of 50% or more was obtained.

  In the end face portion in FIG. 12, the ultrasonic vibration becomes grinding parallel to the processing surface, and the motility of the abrasive grains is increased, resulting in low damage processing that causes cavitation on the parallel surface. As a result, in the right figure, which is a grinding process by simply rotating the notch grinding wheel 72, streaks due to the abrasive grains contained in the notch grinding wheel 72 are recognized on the surface to be ground, but the grinding process with ultrasonic vibration is applied. In the left figure, the movement of the abrasive grains becomes a cross hatch locus, and the striations are flattened.

  In FIG. 12, the count of the notch grinding wheel 72 is set to # 3000. However, the surface roughness of the surface roughness of 1.6 .mu.m obtained by only rotating the surface is 1.6 .mu.m. It was 4 μm, and an improvement effect of 70% or more was obtained.

  As described above, in the grinding process of the notch groove to which ultrasonic vibration is applied, the notch grinding wheel 72 rotates and is subjected to ultrasonic vibration in the axial direction. Can be realized. And the burden of grinding | polishing which is a post process is reduced, the shape at the time of grinding is maintained after grinding | polishing, and an exact shape can be formed. In addition, by improving the processing efficiency, clogging prevention, and processing performance, the shape accuracy and the grindstone life can be improved. The cleaning of the grinding surface and the discharge of grinding scraps can be promoted to maintain the grinding performance or maintain the accuracy of the grindstone shape.

  Furthermore, even when the end face is not chemically strengthened, a good machined surface roughness can be obtained, and the occurrence of microcracks can be suppressed. As a result, the production efficiency is greatly improved, and a practically sufficient end face strength can be obtained.

  Furthermore, not only the surface roughness, but also the number of sheets that can be processed continuously after the grinding groove is corrected once (tooling) and the grinding ability is reduced, the predetermined outer peripheral surface width, outer peripheral angle and outer peripheral shape are not satisfied. Can be increased.

  In the above description, the grinding process using the notch grinding wheel 72 with ultrasonic vibration of the notch groove has been described. However, the orientation flat, the chamfering process at the outer peripheral part of the wafer, and the surface having a straight part other than a circle at the end of the planar shape. You may apply to the end surface processing of a workpiece. In addition, not only semiconductor wafers such as silicon wafers used in the manufacture of semiconductor devices, but also various materials such as silicon, sapphire, compounds, and glass, and high-precision chamfering at the end faces of plate-like workpieces such as glass panels It is also effective for processing.

  DESCRIPTION OF SYMBOLS 1 ... Notch groove, 10 ... Processing part, 11 ... Single-crystal block, 12 ... V-shaped cross-sectional groove, 13 ... Flat surface, 14 ... Orientation flat, 20 ... Supply recovery part, 30 ... Wafer cassette, 31 ... Cassette table, 40 ... Supply and recovery robot, W ... Wafer, 50 ... Transfer arm, 60 ... Wafer feeding device, 61 ... Notch grinding device, 62 ... Outer grinding device, 63 ... Transfer arm, 66 ... Chuck table, 68 ... Outer spindle, 69 ... Outer Grinding wheel, 71 ... grinding spindle, 72 ... notched grinding wheel, 72-1 ... groove, 72-2, 72-3 ... slope, 72-4 ... groove, 73 ... tool holder, 74 ... bearing part, 75 ... vibration Part

Claims (8)

A chamfering grinding method for grinding an end face of a plate-shaped workpiece with a grinding wheel rotating around a rotation axis,
The grinding wheel has a groove portion that is a processing groove parallel to the axial direction of the rotating shaft, and slopes formed above and below the groove portion,
Rotating the grinding wheel and applying ultrasonic vibration in the axial direction;
Grinding by pressing the working groove against the end face of the workpiece from the vertical direction and abutting it ,
A chamfering grinding method characterized in that the count of the slope is larger than the count of the groove and the abrasive grains become finer . The chamfering grinding method according to claim 1,
A chamfered notch groove is formed by pressing and abutting the processed groove in a vertical direction on an end surface of a sliced V-shaped cross-sectional groove formed on the outer peripheral surface of the workpiece. Grinding method. The chamfering grinding method according to claim 1 or 2,
A chamfering grinding method, wherein a width of the processing groove is set to be larger than an amplitude of the ultrasonic vibration with respect to a thickness of the workpiece. A chamfering grinding method according to any one of claims 1 to 3 ,
The grinding wheel is attached as a replaceable to a grinding spindle provided with a vibration unit that rotates the grinding wheel and applies the ultrasonic vibration to the grinding wheel.
A chamfering grinding method, wherein a diameter of the grinding wheel is made smaller than a diameter of the vibrating portion. In a chamfering grinding apparatus for grinding an end face of a plate-shaped workpiece with a grinding wheel rotating around a rotation axis,
A grinding spindle that rotates the grinding wheel and applies ultrasonic vibration to the axial direction of the rotation shaft;
The grinding wheel has a groove portion parallel to the axial direction as a processing groove, and slopes formed above and below the groove portion,
The count of the slope is larger than the count of the groove, so that the abrasive grains become finer,
A chamfering grinding apparatus characterized in that the machining groove is pressed against an end face of the workpiece from the vertical direction for grinding. In the chamfering grinding apparatus according to claim 5 ,
The grinding apparatus forms a notched groove chamfered by pressing the processed groove in a vertical direction on a sliced V-shaped cross-sectional groove formed on the outer peripheral surface of the workpiece. apparatus. The chamfering grinding apparatus according to claim 5 or 6 ,
The chamfering grinding apparatus according to claim 1, wherein a width of the processing groove is larger than an amplitude of the ultrasonic vibration with respect to a thickness of the workpiece. The chamfering grinding apparatus according to any one of claims 5 to 7 ,
The chamfering grinding apparatus is characterized in that the grinding wheel is attached to the grinding spindle provided with a vibration part for applying the ultrasonic vibration so as to be replaceable, and the diameter of the grinding wheel is smaller than the diameter of the vibration part. .